单项选择题
It is hard to tell whether we are going to have a boom in the economy or a （）
A．concession B．recession C．submission D．transmission
单项选择题 The （）from childhood to adulthood is always a critical time for everybody.
单项选择题 If you want this painkiller, you'll have to ask the doctor for a （）
单项选择题 The passage tells us that proof of life on Mars would （）
