把下列句子变为被动语态,
问题描述：
把下列句子变为被动语态,
1.He often helps Tom when he is in trouble.
2.We saw a small boy lying on the ground.
3.We heard her sing at the party last Sunday.
4.We should speak to old men politely.
5.We will plant millions of trees this year.
答
1.Tom is often helped by him when he is in trouble.2.A small boy was seen lying on the ground by us.3.She was heard to sing at the party last Sunday by us.4.Old men should be spoken to politely by us....