三、句子的单复数互换
句子的单复数转换的规则是:对应句中的名词、代词、动词等,能变则变,不能变的,要么保留,要么去掉。要做到熟练掌握并运用这一规则,必须掌握名词的单复数的变化规则,代词对应的人称和单复数,动词的第三人称单数的变化规则等。在解题过程中,还必须具体情况具体对待。
eg. (1) The girl is from England .
→ The girls are from England .
(2) He is a polite and helpful boy .
→ They are polite and helpful boys .
上述例句中,划线的为能变的,没划线的为该保留的,加 号的a(an)为该去掉的。反之,在由复数变为单数时,则要根据句意在名词之前补上一个a (an)。
eg. They are English girls .
→ She is an English .
但是对于"There be"句型,单复数转换时句中的 a / an不能去掉,而要根据句式将其与some或any 互换。
eg. (1) There is a boat on the lake .
→ There are some boats on the lake .
(2) There isn't a tree behind the house .
→ There aren't any trees behind the house .
(3) Is there a pet dog in your home ?
→ Are there any pet dogs in your home ?
(4) There aren't any pictures on the wall of our classroom .
→ There isn't a picture on the wall of our classroom .