每个Applet程序必须有一个类是______类的子类。

为证明细菌对植物遗体的分解作用，某小组的同学分别提出了以下四种实验方案（他们将同一种树的落叶分成甲乙两组，实验过程中在树叶上滴加蒸馏水），其中更能说明问题的实验方案是（　　）

A．将甲组放在无菌条件下，乙组暴露在空气中

B．将甲组灭菌后放在无菌条件下，乙组暴露在空气中

C．将甲乙两组都进行灭菌，甲组放在无菌条件下，乙组接种细菌后放在无菌条件下

D．将甲乙两组都进行灭菌，甲组放在无菌条件下，乙组接种细菌后暴露在空气中

网上银行个人质押贷款单笔（户）贷款总额不得超过（）万元。

A、50

B、100

C、500

D、1000

The owner of a bowling alley determined that the average weight for a bowling ball is 12 pounds with a standard deviation of 1.5 pounds. A ball denoted "heavy" should be one of the top 2 percent based on weight. Assuming the weights of bowling balls are normally distributed, at what weight (in pounds) should the "heavy" designation be used（）

A. 15.08 pounds.

B. 14.00 pounds.

C. 14.22 pounds.

In a competitive market, the gains to society are maximized under which of the conditions described belowMarginal Benefit Marginal Cost Producer Surplus Consumer Surplus（） ①A. $1.25$1.00$25 $25 ②B. $1.50$1.50$45 $30 ③C. $2.50$2.50$35 $35

A. ①

B. ②

C. ③

治疗气虚阴挺的最佳选方是

A．圣愈汤

B．六君子汤

C．四君子汤

D．大补元煎

E．补中益气汤