3．frightened；frightening　frightened 受惊的，害怕的；frightening 使惊恐的。

　　4．to come　be unlikely to do sth.不可能做某事。

　　5．who　定语从句缺少主语，且先行词指人，故此处用who引导定语从句。

　　6．thousands　thousands of 数以千计的。

　　7．about/of　be sceptical of/about sth. 怀疑某事。

　　8．whom　该定语从句的先行词指人，且most of__________在从句中充当主语，空处位于介词后，故用whom。

　　9．a　"不定冠词＋序数词＋名词"表示"再......，又......"。

Ⅱ.单词拼写

　　1．On his way home，he was__________(袭击)by two strangers.

　　2．It was a very__________(吓人的)experience and they were very brave.

　　3．So far there has been no proof that people from other planets do__________(存在)．

　　4．We couldn't cut the string because the edge of the knife was not __________(锋利的)enough.

　　5．Egypt，as the birthplace of ancient civilization，is a__________(神秘的)land.

　　6．He once__________(声称)to be a journalist.

7．Water covers a large proportion of the earth's__________(表面)．