1.表示条件： if, unless，so long as, in case(万一)，on condition that, only if，providing/provided that, suppose/supposing that(倘若假使) 等。
例一In time of serious accidents, ___we know some basic things about first aid, we can save lives.
A. whether B. until
C. if D. unless
例二 We won’t keep winning games _____we keep playing well.
A. because B. unless
C. when D. while
例三 Leave your key with a neighbor ___ you lock yourself out one day
A. ever since B. even if
C. soon after D. in case
例四 —— What are you going to do this afternoon?
—— I’ll probably go for a walk later on it stays fine.
A.as far as B.so long as
C.even if D.as if
例五 John's mother allowed him to go swimming ___that he didn't go too far from the bank.
A. if B. unless
C. when D. on condition
2.表示让步： though, although, even if，even though，as(让步倒装)，while ( 一般用在句首 ), in spite of the fact that, no matter …，whatever, whoever, wherever, whenever, however, whichever等。
例一 We had to wait half an hour ______ we had already booked a table.
A. since B. although
C. until D. before
例二Many of them turned a deaf ear to his advice, _______ they knew it to be valuable.
A. as if B. now that
C. even though D. so that
例三 We won’t give up we should fail 10 times.
A.even if B.since
例四Your uncle seems to be a good driver ; ______ ,I wouldn’t dare to travel in his car .
A.even so B.even though
例五 ______ happens, we should never lose hope.
A.No matter what
B.no matter whatever
例六 You should try to get a good night’s sleep much work you have to do .
A.however B.no matter
例七He tried his best to solve the problem, _______difficult it was.
A. however B. no matter
C. whatever D although
3.表示方式：as, as if, as though, the way，how等。
例一 It looked ___ it was going to snow.
A. as if B. if
C. as D. whether
例二 We must do the experiment ______the teacher does.
A. whatever B. as
C. how D. when
4.表示目的： that，so that, in order that, in case that, lest, for fear that，in case, for fear that，in the hope that, for the purpose that, on purpose that等。
例一 Roses need special care _____ they can live through winter.
A. because B. so that
C. even if D. as
例二 My parents live in a small village. They always keep candles in the house _____ there is a power out.
A. if B. unless
C. in case D. so that
例三He whispered to his wife_______ he might wake up the sleeping baby.
A. so that
B. on condition that
C. for fear that
D. so long as
5.表示结果：so…that, so that, such…that, that等。
例 His plan was such a good one _____we all agreed to accept it.
A. so B. andC. that D. as
6.表示地点：where, wherever，anywhere, everywhere等。
例一 If you traveling ____the customs are really foreign to your own, please do as the Romans do.
A. in which B. whatC. when D. where
例二 —— Mom, what did your doctor say?
—— He advised me to live _____the air is fresher.
A. in where
B. in which
C. the place where