管路系统的特性曲线是随着（）的增加而上升。
A、流量
B、扬程
C、轴功率
D、效率
参考答案：A
His sister left home in 1998, and _____ since. [ ]
A. had not been heard of
B. has not been heard of
C. had not heard of
D. has not heard of
近代不平等条约中赔款数目最多的是《马关条约》。
错误：_________________________订正：_________________________
