________ it rained very hard ,_______ they all went on working in the fields.[ ]   

A. Though；but

B. Though；yet

C. But; though

D. Although; but

因为制作时加入油，炕制丹麦牛角包时加温时间（），否则不脆。

A、长

B、短

C、不变

D、视气候而定