16. We were struck by the extent ________ which teachers‘ decisions served the interests of the school rather than those of the students.

A) to B) for C) in D) with

17. Shelly had prepared carefully for her biology examination so that she could be sure of passing it on her first ________.

A) intention B) attempt C) purpose D) desire

18. The store had to ________ a number of clerks because sales were down.

A) lay out B) lay off C) lay aside D) lay down

19. All the students in this class passed the English exam ________ the exception of Li Ming.

A) on B) in C) for D) with

20. Writing is a slow process， requiring ________ thought， time， and effort.

A) significant B) considerable C) enormous D) numerous

6-20 ABBDB