石膏板分为纸面石膏板和纤维石膏板,纸面石膏板是纤维石膏板的改进材料。
参考答案:错
酸性气中带烃对装置有何影响?
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.