改成被动语态

1,old people should be spoken to politely.
2.waste paper should not be thrown on the ground.
3.does your parcel usually be sent by email or by surface mail?

1old people must be spoken in a polite way.
2waste paper should not be thrown on the ground, please.
3do the parcel usually be sent by air mail or by surface mail by you?

1.Polite words must be sopken to old people by every one.
2.Waste paper should not be thrown on the ground.
3.Your parcel is usually sent by air mail or by sufrace mail?
我想应该是这样吧?如果知道了真正答案时能不能告诉我一声呢.我也在学呢.谢咯~

1.Old people must be spoken to politely.

2.Waste paper should not be thrown on the ground.

3.Is the parcel usually sent by air mail or by surface mail ?