二、句子谓语动词一定用复数的两种情况：
1. 集合名词做主语，集合名词没有复数形式，因为他本身就代表一个复数概念。
常见的几个复合名词： people 人民，人们; police 警察; cattle 牛; poultry 家禽。
2. 表示数量的复数名词 + 不可数名词，整体做主语时
例如：去年出口了八百万顿煤。 eight million tons of coal were exported last year.
三、谓语动词一定用单数的六种情况：
1. 句子的主语是由从句充当的、动词不定式短语作主语、动名词短语作主语;
2. 表示时间、重量、长度、价值四方面的词做主语;
399. —— “how many days?”
0 —— “did you say that five days _c_ required to complete that work?”
a are b were c was d is
3. 表示单数概念的主语，短语，谓语动词，此时谓语动词也用单数;
因为此结构中短语只是对主语提供附加说明情况，所以谓语动词也用单数。
当以下这些标志性的介词或介词短语出现在此结构中时可以不管中间的附加说明情况：
with， together with， like， except， besides， in addition to， rather than， as well as
注意：表示复数概念的主语，短语，谓语动词，此时谓语动词应用复数。
4. each， every， either， some， any， no，由以上六个词中任何一个所构成的复合代词作主语时;
some经常构成的三个复合代词：something， somebody， someone;
no经常构成的三个复合代词：nothing， nobody， no one; either of + 短语;
5. 通常由and连接两部分这种形式做主语谓语动词要用复数，但在以下两种情况下则应用单数;
1》 and连接的两部分指的是同一事物;
2》 and连接的两部分被no， each， every中任何一个词修饰时;
例如：每位男士和女士都要着装得体。 be supposed to do sth. 理应，应该做某事。
every man and every woman is supposed to dress properly.
11. many an airplane _b_ in the exhibition.
a are shown b has been shown c has shown d show them
many a（an） 很多，相当于many; many a（an） + 可数名词单数，做主语时谓语动词用单数。
6. many a （an） + 可数名词单数，作主语时谓语动词用单数。
9. not only joan but her sisters _b_ the combination to the safe which contains the list of the family securities.
a have known b know c knows d is knowing
not only … but also … 的一种变形形式，not only … but …
另一种变形形式not only … but … as well
combination n. 密码; combination to the safe 保险箱密码; securities有价证券。
41. she ought to stop work; she has a headache because she _a_ too long.
a has been reading b had read c is reading d read
had read 过去完成时要与一般过去时搭配。
has been reading 现在完成进行时：指某行为从过去一点到现在一直在进行。
42. niagara falls is a great tourist _b_， drawing millions of visitors every year.
a attention b attraction c appointment d arrangement
tourist attraction 旅游胜地; attention n. 注意力; appointment n. 委任的职位，约会;
date n. 日期，约会，枣;表示约会时指的是异性之间的私人约会。 arrangement n. 布置，安排
blind date 两人第一次见面的约会。 appointment 指公事性质的，比较正式的约会。