骨髓瘤好发于下列哪些部位（）
A.肱骨
B.脊椎
C.肋骨
D.骨盆
E.胸骨
参考答案：B, C, D, E
Although it is _____ to watch programs on TV sometimes, I think people shouldn’t spend all the time watching it.
A．worthwhile
B．worthy
C．worth
D．worthy of
下列选项中，（）能促进插穗生根。
A、移植
B、带踵扦插
C、插穗倒插
D、曝晒插穗
