8)    A to change         B to make        C making        D changing

9)    A from             B into            C to            D form

10)   A away from        B out of            C into         D under

11)   A having doing     B doing            C do          D to do

12) A untouching      B untouched         C touching      D touched

13)   A great          B large             C big           D greater

14)   A on             B aloud           C through        D about

15)   A when           B which          C before         D as

16)   A dogearing     B dogeared          C to be dogeared   D to dogear

17)   A marking up     B mark up           C to mark up      D to mark

18)   A wake        B wake up           C awaking        D awake

19)   A tend to       B tends to           C tending to       D tending

20) A expressing     B to express       C expressed          D to expressing

参考答案:
1--5       ACBAD 
6--10     CBBAC

11--15   DBACD
16--20   BADBC