Scientists say it may be five years _____ it is possible to test this medicine on human patients.[ ]

You can’t imagine what great trouble the doctor had ______ the patient

Are all the students from in your class—No, there are only three in our class. The others are from other countries.

What color is it — It’s _______ orange. It’s _______ orange pen.

Once new difficulties _____ in our new job, we should learn to use our brain to deal with it.