计算x6÷x3的结果是（ ）
A．x9
B．x3
C．x2
D．2
x6÷x3=x6-3=x3．
故选B．
He thinks watching movies ________.
A．frustrated
B．frustrating
C．frustrate
D．to frustrate
影响引种驯化成败的因子？引种驯化时应注意的问题？引种驯化时应考虑的因素？
