There is still some doubt ______ he is innocent—That’s why he was accused ______ the crime

I am very worried about tomorrow’s chemistry test. I’ m afraid I can’t pass this time.— ! I’m sure you’ll make it.

China’s population is expected to increase to about 1.5 billion in 2040, ______it will start to decline slowly.

The resethe job—____ my students have a try

Without the contributions of Qian Xuesen, the father of Chinese missile, the achievements in space technology unthinkable in China．