下列化学式既能表示物质的组成,又能表示物质的一个分子的是 ( )
A.NaOH
B.SiO2
C.Fe
D.CO2
答案:D
下列机构中,有权依法制定政府规章的是( )。
A.某直辖市人民代表大会B.某省人民政府的工作部门C.某自治区人民代表大会常务委员会D.某省人民政府所在地的市人民政府
Damaged nerves in the spinal cord do not regenerate themselves naturally, nor even under the spur of nerve-growth stimulants. The reason, recently discovered, is the presence of nerve-growth inhibitors in the spinal cord. Antibodies that deactivate those inhibitors have now been developed. Clearly, then, nerve repair will be a standard medical procedure in the foreseeable future. Which of the following, if true, casts the most serious doubt on the accuracy of the prediction above
A.Prevention of the regeneration of damaged nerves is merely a by-product of the main function in the human body of the substances inhibiting nerve growth.
B.Certain nerve-growth stimulants have similar chemical structures to those of the antibodies against nervegrowth inhibitors.
C.Nerves in the brain are similar to nerves in the spinal cord in their inability to regenerate themselves naturally.
D.Researchers have been able to stimulate the growth of nerves not located in the spinal cord by using only nervegrowth stimulants.
E.(E) Deactivating the substances inhibiting nerve growth for an extended period would require a steady supply of antibodies.