运输供给能力受运输基础设施条件变化影响将呈现()变化。
A.阶梯性
B.波动性
C.平行性
D.分散性
参考答案:A
解析:本题考查运输供给的特点。运输供给能
You can hardly imagine the once clear canal _____ so seriously polluted that no fish can live in it. [ ]
A. have become
B. having become
C. to have become
D. to become
斜长石有()和(),而无()和()。