I have problems _______many things. For example, I have problems ________ learning Maths well.
—Is this ______ model plane? —No, it isn’t ______.
—Who’s that at the door? —_____ is John.
如果你向玛丽介绍自己,你应该说:_______
— Your bag looks heavy. Do you need a hand? — . Thanks all the same.
---What are you going to do this weekend?----- I _____ yet.