【单选题】It can be inferred from the passage that scientists are 'perplexed by the means' (line 12) for which of the following reasons?
A.
They are unsure of how alanine remains separate from the everyday nitrogen metabolism of the plant itself.
B.
They have yet to establish what function the alanine serves for the soybean plants.
C.
They have thought alanine to exist only in very small quanties in rhizobia.
D.
They have long considered the membranes of the soybean plant impermeable to amino acids.
E.
They are uncertain how such a rapid export of fixed nitrogen is possible through the soybean membranes.
【单选题】That large regions of the galaxy can be influenced by the formation of massive stars in a few localized regions requires that star formation somehow be coordinated over long periods of time. The proce...
A.
indicate the direction that research into a particular physical phenomenon should take
B.
illustrate the limitations of applying mathematics to complicated astrophysical phenomena
C.
clarify the differences between an old explanation of a physical phenomenon and a new model of it
D.
introduce a new explanation of a physical phenomenon
E.
explain the difference between two related physical phenomena
【单选题】A splice that can be used in running rigging,where the line will pass through blocks,is a().
【简答题】 The line can be long, but it's _________ it, promise. 队排的有点长,但是我保证绝对值得。
【多选题】汽车的制动系统一般包含()这几个组成部分。
【单选题】A splice that can be used in running rigging,where the line will pass through blocks,is a().
【单选题】刘奶奶,79岁,因病情急剧恶化,已处于临终状态,护理该病人的主要措施是
【单选题】A long statement can be split across multiple lines by ending each line, except the last, with the character(s) ____________.