问题
选择题
Climbing Mount Tai great skills and not without risk.
A．requires; is
B．required; was
C．required; are
D．required; were
答案
答案：A
本题考查时态。and连接两个并列的谓语动词，陈述的是客观事实，用一般现在时；主语都是Climbing Mount Tai。Doing 形式作主语谓语动词用单数。