Now class please turn to (page 9)and read after me
为什么不是pages?
She has (an 8-year-old boy)
为什么不是an 8 years old boy?
tom, (add) 3 and 2
tom不是第三人称单数吗,为什么不加s
The river is about (five hundred metres)long
为什么不是hundred加s?
I have two (pairs of trousers)
为什么pair和trouser都要加s?