铁路中间站的间距一般为( )km。
A.8~12
B.15~20
C.20~40
D.30~60
参考答案:C
Tom hid himself behind the door, _________ he could hear the steps of his mother clearly.
A.from which
B.from where
C.where
D.which
We have received orders()US$1,000,000 since the new product was introduced to the market.
A.amountfor
B.amountto
C.accountfor
D.amountingto