题目

Having a trip abroad is certainly good for the old couple, but it remains ______ whether they will enjoy it.    A. to see                   B. to be seen             C. seeing                 D. seen 答案：B12．下列各项属于行为信息的是（　　）A．蚊子飞翔时发出声音B．警犬嗅寻毒品C．豪猪遇敌时竖起体刺D．海豚借助超声波确定方位