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。

Your       as a student will be excellent if you develop a habit of reflecting on how you learn.

operation

growth

performance

character

考查名词辨析。句意：作为一名学生，如果你养成课后复习的好习惯，那么你的表现就会很优异。A.operation 操作； B. growth生长；C. performance 表现；D.character性格。学生如果有课后复习的好习惯，会表现优秀。故选C项。

So difficult __________ it to work out the problem that I decided to ask Tom for advice.

 I did find 

did I find

 I have found  

have I found

句子使用的基本句式为so…that…结构。按英语语法，当该结构的so…置于句首时，其后的句子(主句)要用倒装语序，如：So loudly did he speak that even people in the next room could hear him. 他讲话声音那么大，隔壁屋里的人都听得见。

I can't tell you         way to the Wilson's because we don't have        Wilson here in the village.

a; /

the; a

a; the

the; /

考查冠词。句意：我无法告诉你去威尔逊的路，因为我们村没有一个叫威尔逊的人。the way to...去.....的路，这里是特指去威尔逊家的路，用定冠词the,排除A、C;第二空泛指一个叫威尔逊的人，应该

用不定冠词，a Wilson 一个叫威尔逊的人，排除D项。故选B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。

It’s his brother ______ never been to Australia. You’d better take him with you.

that is

who is

that have 　

 who has

句意：就是他的弟弟从没去过澳大利亚。你最好带他和你去。根据句意及题干分析此题是考查强调句型，因为强调的是his brother，是人，所以用who引导是现在完成时态，故选D。

Mary and her friend          a plan and gathered forty people from my company to help the homeless people at the Christmas party.

came up with

put up with

caught up with

kept up with

考查动词短语辨析。句意：玛丽和她的朋友想出了一个计划，在圣诞节聚会上，从我的公司聚集了四十几个人来帮助无家可归的人。A. came up with 提出；B. put up with 忍耐；C. caught up with追上，赶上；D.kept up with 跟上。下文“聚集人帮助无家可归的人”是想出的计划。故选A项。