问题
选择题
—Where is Bob? I cannot find him anywhere.
—He have been off long. I heard him make a call just now.
A．shouldn’t
B．can’t
C．mustn’t
D．needn’t
答案
答案：B
考查情态动词与虚拟语气用法。语境表示语气很肯定的否定判断推测：我刚才还听见他打电话了，因此他一定没走多远。用can’t have done。