实土卫所

采样阶段影响煤样代表性的因素有（）、（）和（）。

Scientists _____ DNA from one kind of plant and _____ it into another kind of plant to make a pretty new one. [ ]

A. take, give

B. make, put

C. make, give

D. take, put

若深度为5的完全二叉树的第5层有3个叶结点，则该二叉树一共有______ 个结点。

A．15

B．16

C．17

D．18

It is absolutely essential that William ______ his study in spite of some learning difficulties.[ ]

A. continue

B. continued

C. has continued

D. would continue

仿照示例扩写，要求意蕴丰厚，有文采。（6分）

栏

倚栏。

倚栏远眺。

倚栏远眺，烟波江上使人愁。

月。