单项选择题
Mary () in bed all day because she had a fever.
A. lay B. has laid C. has lain D. laid
单项选择题 He is so shy that he() speaks in the public.
单项选择题 In countries where a solar calendar was adopted, the length of each year need to be () in order to have the same number of months in each year.
单项选择题 Had he worked harder, he () the exams.
