you have tried it on you can’t imagine pretty the new style skirt is.A. Because; howB.

问题补充：

you have tried it on, you can’t imagine pretty the new style skirt is.

A. Because; how

B. Unless; how

C. If; what

D. Although; what

答案：

A. Because; how

(答案→)B. Unless; how

C. If; what

D. Although; what

解析：句意：除非你已经尝试了，你无法想象这新款的裙子是多么漂亮。Because连接原因状语从句，unless与if连接条件状语从句， Although连接让步状语从句。根据句意前后是条件关系，unless=if…not，后面是否定，前面用unless. 后面的句意是重点修身形容词pretty, 所以应该用how。故选B。