_______ difficult and challenging the task may be, we must finish it on time, because there is a possibility _______our work will go down in history.

A．Whatever; that

B．However; as

C．Whatever; which

D．However; that

有关SCAN循环结构，叙述正确的是 ______。

A．SCAN循环结构中的LOOP语句，可将程序流程直接指向循环开始语句SCAN，首先判断EOF()函数的真假

B．在使用SCAN循环结构时，必须打开某一个数据库

C．SCAN循环结构的循环体中必须写有SKIP语句

D．SCAN循环结构，如果省略了＜scope＞子句 \FOR＜expll＞和WHILE条件子句，则直接退出循环