Because the shop the T-shirts are sold at half price.A. has closed downB. closed downC.

问题补充：

Because the shop , the T-shirts are sold at half price.

A. has closed down

B. closed down

C. is closing down

D. had closed down

答案：

A. has closed down

B. closed down

(答案→)C. is closing down

D. had closed down

解析：T桖杉正以半价销售，这说明商店还没关张，故选C项，用现在进行时表示将来的动作。