His earnings were only half the amount___ A.they used to be B.they used to 为什么选A,不选B.
问题描述：
His earnings were only half the amount___ A.they used to be B.they used to 为什么选A,不选B.
答
在跟过去做对比时,前后动词必须一致,其他动词可省略但 be 动词不可.例如：His weight is twice as much as it used to be.主语是 his weight ,后半句中由 it 替代了；谓语是 be 动词.He weighs twice as much as he ...