影响需求的因素有______。 A．价格 B．收入水平 C．偏好 D．消费者预期

下列专门成本中相关性一致的有（）。

A．机会成本

B．账面成本

C．过去成本

D．不可避免成本

图中，太阳光通过三棱镜后，分解成七色光带，其中光屏上端是   色光，这是英国物理学家

   首先通过实验研究得到的光的   现象。

于主动脉瓣第二听诊区闻及高音调的舒张期杂音，提示

A．干下型室间隔缺损合并主动脉瓣关闭不全
B．室间隔缺损合并动脉导管未闭
C．房间隔缺损合并动脉导管未闭
D．室间隔缺损合并肺动脉高压
E．动脉导管未闭合并肺动脉高压

The news of the first successful cloning of a sheep has sent shock waves around the world．As a result, in many countries, officials and even some scientists are calling for new or strengthened legislation to outlaw human cloning, although at this early date, no concrete measures have been proposed．In the United States, which currently has no law prohibiting the procedure, President Clinton announced an urgent inquiry into the potential ethical and legal implications bythe National Bioethics Advisory Commission, which will report its conclusions by the end of May. Meanwhile, Clinton has banned federal funding for human cloning research and asked for a moratorium on nonfederally funded efforts. In addition, both houses of the U. S. Congress had held holding hearings on the issue. Scientists have cloned embryos for the first time from patients with serious diseases and injuries. It is believed that the day will come when some of mankind’s most destructive diseases and injuries can be effectively treated through the use of therapeutic stem cells.

热电偶温度计的测量范围为（）。

A.0℃～2000℃

B.0℃～1000℃

C.700℃～2000℃

D.0℃～700℃