Interferon has not been widely used because it is________.
A. still very dangerous
B. not yet available in the United States
C. difficult to produce in large quantities
D. not effective for human beings
查看答案
用0．10 mol·L-1 NaOH滴定0．10 mol·L-1 HAc时的pH突跃范围为7．7～9．7，由此可知用0．010 mol·L-1 NaOH滴定0．10 mol·L-1 HAc时的pH突跃范围为()。
A. 6．7～8．7
B. 6．7～10．7
C. 7．7～8．7
D. 7．7～10．7
The phrase "function in the disservice of one another" (Lines 7~8, Para. 1) most probably means______.
A. betray each other
B. harm one another
C. help to collaborate with each other
D. benefit one another
Which of the following is NOT mentioned in the passage as influencing the migration of locusts？
A. Darkness.
B. Agricultural activities.
C. Warm air currents.
D. Overcrowding.
The passage supports which of the following conclusions？
A. The outbreak of locusts in 1938 was more serious than any other in history.
B. Nebraska farmers had no locust problems in the years 1874—1877.
C. There is a possibility that crops in the Unite States might be destroyed by locusts in the future.
D. There is a chance that African migratory locusts may make their way to the United States.
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