下列属于南美洲的地形是[ ]
A、印度河平原
B、亚马孙平原
C、落基山脉
D、刚果盆地
答案：B
Do you know_____ ?[ ]
A. he is a Canadian athlete
B. is he a Canadian athlete
C. whether he is a Canadian athlete
什么是细胞核与细胞质之间的通道（）
A．核膜
B．胞间连丝
C．核膜孔
D．外连丝
