Some diseases are present by heredity.

有些病是遗传的结果。

I sent her birthday present by post.

我送她的生日礼物是邮寄的。

She sent me the present by parcel post.

她用邮包把礼物寄给了我。

I was bought a Christmas present by my father.

我父亲给我买了一件圣诞礼物。

The disease is being studied at present by scientist.

现在正在研究熊猫的生活环境。