Grammar – In case, Unless, As long as

–This section will cover a broad range of different grammar rules and explanations to help you understand sentence structure and improve awareness of English grammar.
Learning to use: "in case", "unless", and "as long as"

Today we are going to learn how to use "in case", "unless" and "as long as". Each word/phrase can have a similar meaning with one another, so make sure you learn how to use them.

1. in case = ~の場合に備えて
  Ex.1: Ann might call tonight, I don’t want to go out in case she calls.(アンが電話してくるといけないから、出かけたくない)
  Ex.2: I’ll draw a map for you in case you can’t find our house.(私たちの家が見つけられないといけないから、地図を描いておいてあげる)
"in case"は「~のために事前に備えて」という意味で使われます。「もし~ならば」の意味をもつ"if"とは意味が違いますので注意しましょう。
2. unless = もし~でなければ
  "if"つまり「もし~ならば」の正反対として使われます。= if not

Ex 1: Unless I study grammar, I won’t be able to speak English.(もし文法の勉強をしなければ、英語を話せるようにはならない。)

  Ex 2: I’m playing tennis tomorrow unless it rains (もし雨がふらなければ、明日テニスをする)
  Ex 3: You don’t have to go to school unless you want to (もし行きたくないのであれば、学校に行かなくていいよ)
3. as long as = 「~である限り(これが条件である)」
  Ex 1: You can use my car as long as you drive carefully.(気をつけて運転するのであれば、私の車を使ってもいいよ)
  Ex 2: As long as she continues to study hard, she will pass her exam.(一生懸命勉強を続けている限り、彼女は試験に合格するだろう)
  Ex 3: It doesn’t matter how expensive your vacation was as long as you enjoyed yourselves.(楽しめたのであれば、旅行がどれだけ高かったとしても関係ないよ)※"If"に近い形で使われているが、それより強い意味が込められている
"as long as"は「~である限り」という意味を持ち、"if"「もし~ならば」よりさらに強く表現をする時に使われます。
Check your understanding of the above grammar:
Read each of the following of sentences and select the best answer. Print out this lesson plan and ask your teacher to assist you in understanding the grammar rules.
1 I will leave my cell phone on (in case / unless) my mother calls.
2 You should bring an umbrella (in case / unless) it rains.
3 (In case / Unless) you intend on going out tonight, there is no need to dress up.
4 I drew a map for Tomoko (in case / unless) she got lost trying to find where I live.
5 We can take a taxi to the station (in case / unless) you prefer to walk.
6 I can probably meet you at 8pm (in case / unless) my boss asks me to work late.
7 People can use either the express or normal elevators (in case / unless) there is a fire.
8 You should register your iphone with icloud (in case / unless) it gets lost or stolen.
9 Take some chocolate with you (in case / unless) you get hungry.
10 (In case / Unless) it rains tomorrow, the picnic will be held as scheduled from 1pm.
Moderate level exercises:
Read each of the following of sentences and write whether : unless, in case, or as long as is needed. Print out this lesson plan and ask your teacher to assist you in understanding the grammar rules.
1 As long as it does not rain, we will probably go ahead with the picnic.
2 This letter is for Mr. Thompson. Can you give it to him in case you see him.
3 You can not enter that gym unless you are a member.
4 Unless my company gives me a promotion and more time off each year, I will most likely take the job offer from the competing firm.
5 I don’t think you should tell Rena that her boyfriend is cheating on her unless she confronts you about it.
6 As long as you promise to fill up the tank when you return it, I see no problem in letting you borrow my car.
7 There is no public transportation to the beach. Unless you have a car or can get access to one, I don’t think you will be able to go.
8 I’m playing tennis tomorrow unless it rains.
9 Children under the age of 12 are permitted to use the swimming pool as long as they are accompanied by an adult.
10 Unless they are dogs that assist in guiding the vision impaired, this hotel establishment does not allow pets.
Difficult level exercises:
Read each of the following sentences and write a sentence using either unless or as long as:
1 The club isn’t open to everyone. You are allowed in only if you’re a member.
Unless you are a member, you will not be allowed into the club.
You are allowed into the club as long as you are a member.
2 She has to sincerely apologize to me, or I will never speak to her again.
I will never speak to her again unless she sincerely apologizes to me.
As long as she is sincere in apologizing to me, I will speak to her again.
3 Don’t worry about the dog. It will attack you only if you move suddenly.
The dog will not attack you unless you move suddenly.
As long as you do not move suddenly, the dog will not attack you.
4 The doctor will see you only if it is an emergency.
The doctor will not see you unless it is an emergency.
The doctor will see you as long as it is an emergency.
5 I don’t mind if you come home late. Just make sure you come in quietly.
I don’t mind if you come home late unless you come in noisily.
As long as you come in quietly, I do not mind if you come home late.