This is a set of keys. My pencil is in my pencil case.这是一串钥匙.我的铅笔在我铅笔盒里.
Is this your English book? 这是你的英语书吗?
This set of keys is in his backpack.这串钥匙在他的背包里
This is a set of keys. My pencil is in my pencil case.这是一串钥匙.我的铅笔在我铅笔盒里.
Is this your English book? 这是你的英语书吗?
This set of keys is in his backpack.这串钥匙在他的背包里