6.Ten minus three are seven. (×)
Ten minus three is seven. (√)
[析] 用英语表示加(plus)、减(minus)等数学运算时，谓语动词也用单数形式。
7.The number of the workers in this factory are about 5,000. (×)
The number of the workers in this factory is about 5,000. (√)
[析] the number of表示“……的数量”，谓语动词用单数形式;a number of 的意思是“若干”或“许多”，相当于some或a lot of，和复数名词连用，谓语动词用复数形式。
8. 例. Hello! I have important something to tell you. (×)
Hello! I have something important to tell you. (√)
[析] 形容词或动词不定式修饰不定代词作定语时，修饰成分要置于不定代词之后。
9. His son is enough old to go to school. (×)
His son is old enough to go to school. (√)
[析] enough作形容词修饰名词时，可以放在名词前，也可放在名词后;作副词修饰形容词或副词时，只能放在形容词或副词之后。
10.. Here is your sweater, put away it.(×)
Here is your sweater, put it away. (√)
[析] put away, pick up, put on等“动词+副词”构成的词组后接代词作宾语时，代词只能放在动词和副词之间。