____使得唐朝元气大伤,由盛转衰。
(9153-2319)÷67=____
I have got a new subject-physics this____ (学期).
曲线y=ex在点2,e2处的切线与坐标轴所围三角形的面积为( )
Mr. Green didn't post the letter _________. He asked his son to do it for him.