Like other animals, we are          until we know it is safe to relax.

on purpose

on fire

on guard

on duty

考查介词短语辨析。句意：像其他动物一样，我们在知道安全的时候才放松警惕。A.on purpose 故意；B. on fire着火；C.on guard 警惕；D.on duty值班。结合后文we know it is safe to relax，可知我们在知道安全的时候才放松警惕。故选C项。

Tom wanted to play football with his friends in the street，but his father told him ________.

not to

not to do

not do it

do not to

考查动词不定式的省略。完整的形式应该是…，but his father told him not to play football with his friends in the street.为避免重复，常省去不定式动词，保留不定式符号to，故选A。

Since this accident has nothing to do with him, he seems no way             .

to be blamed

to blame

blame for

to blame for

考查固定用法。句意：既然这次事故与他无关，他似乎也就无可指责了。短语sb to be blame“某人该受责备，某人应该负责”，为固定搭配，没有被动语态。故选B项。

My little sister          me into buying this book.

wanted

advised

persuaded

told

考查动词词义辨析。句意：我的小妹妹说服我买了这本书。A. want想，想要；B.advised 建议；C. persuaded说服，劝服；D.told告诉。want  sb to do sth想要某人做某事；advise sb to do sth 建议某人做某事；persuade sb into doing sth 劝服某人做某事；tell sb to do sth告诉某人做某事。故选C项。

A bank is a place         they lend you an umbrella in a fair weather and ask for it back when it begins rain.

when

where

that 

there

考查定语从句。句意:银行就是一个天气好时借给你雨伞，开始下雨时再要回来的地方。A.when关系副词，做时间状语 ；  B.where关系副词，做地点状语；C.that 关系代词；D.there 那里。分析句子可知，空格处引导定语从句，关系词代替先行词 place，在从句中充当地点状语，应用关系副词where。故选B项。