to nuclear radiation, even for a short time, may produce variants(变异)of genes in human bodies.[ ]

_____ I admit that there are problems, I don’t’ think that they cannot be solved

What do you think of the young boy —He is good ___________ me. He is good ________ English, and he often tells melistening to English songs is good __________ learning it well.

foolish I was!— ________ you have realized that, stop blaming yourself.

The town’s drinking-water _____ with prim chemicals at present