在下列各句的空格内填上一个适当的单词，该词的首字母已给出。

1. I can't hear you. Can you read it a_______?

2. If you work hard, you will s________ in the end.

3. His mother often teaches him the i________ of working hard.

4. Peter f______ his math test last time. He was sad.

5. Though he is much too s_______, he tries his best to keep awake.

药材略呈扁斜方形，外皮黄棕色或黄绿色，两侧各具一条色较浅的斜形凹纹。此药材是

A．菟丝子

B．决明子

C．白芥子

D．牵牛子

E．沙苑子