I first met him_____a hot summer evening.[ ]

What do you usually do _____ weekdays after school? —I usually play football. [ ]

It’s _______of Yang Xiangming to save the boy who fell into the river. — Yes. He is a great man of our times.

Mr Black is at home, but he doesn’t feel .

Scientists are now working _ humanoids(类人生物) because they can help people alot. [ ]