把下列句子变成被动语态：

把下列句子变成被动语态：
He often makes model planes in his spare time.
She taught us geography last year.
He is weighing the stones.
They may offer you a good job.（用两种方法）
I saw Lily taking a walk this time yesterday.
We often hear him sing English songs.
People have made him president.
Did he throw the rubbish just now?
What has Tom bought so far?
Who is using the plastic bags?