车辆在坡度上起步或通过困难路面时应选择（）挡。
参考答案：低速
血清清蛋白降低、球蛋白升高主要见于（）
A.急性病毒性肝炎
B.急性肾小球肾炎
C.胆囊炎
D.肝硬化
E.十二指肠溃疡
What a pity! I hear they _______ the tickets for the concert.[ ]
A. have sold out
B. are selling out
C. sold out
D. had sold out
