四季豆中的植物凝血素有一定的毒性。( )
参考答案：对
He had a wonderful childhood, ________ with his mother to all corners of the world. [ ]
A. travel
B. to travel
C. travelled
D. travelling
下列材料可以做防潮层的有（）。
A、沥青及沥青油毡
B、玻璃丝布
C、铝箔
D、石棉石膏
