21、Because ____ unemployment is very high at present, it's not easy for a fresh graduate to find ____ satisfying job as he wishes．

A．the; /          B．/; a            C．an; a           D．an; the

20、Following the girl, we went into a hall, on ____ walls hung a few pictures of some famous scientists．

A．its          B．which           C．whose           D．those

19、—Those scientists invented a robot to care for kids!

—It's not surprising．They ____ wonders all the time．

A．worked           B．were working           C．work           D．have been working

18、—Quite a lot of students failed in the math exam．

—Exactly．It is ____ their abilities．

A．within          B．over       C．against         D．beyond

17、The purse found on the playground matches the ____ by Mary, so it must be hers．

A．direction       B．description           C．expression               D．instruction

16、Either the ways or the time ____ yet, but you may ask the headmaster for some information．

A．isn't decided         B．hasn't decided         C．aren't decided          D．haven't decided

15、The UN officials say it could be many weeks and even months ____ a deal is reached．

A．before          B．after          C．when         D．as

14、Many children are ____ in the countryside when their parents flood into the cities for jobs．

A．left behind     B．left off           C．left aside         D．left out

13、It is the test system, rather than the teachers, ____ is to blame for the students' heavy burden nowadays．

A．who        B．this          C．that        D．whom