闯关训练
夯实基础
从A、B、C和D四个选项中， 选出可以填入空白处的最佳答案。
1.It is difficult to judge what words are ______ and what words are not.
A.worth to look up                            B.worth being looked up
C.worth looking up                            D.worthy of looking up
解析：短语be worth后面要求跟动名词形式，且用主动形式表示被动的意思，而be worthy后的结构为of being done或to be done。
答案：C
2.（2004年苏、锡、常、镇四市模拟）The brake of your bicycle has come loose.You’d better______it.