The general use of the term "spare" in this text refers to______.
A. any unwanted e-mail
B. any untargeted e-mail
C. any unsolicited e-mail
D. any targeted e-mail
静息状态下K+由细胞内向膜外扩散的机制是
A. 单纯扩散
B. 以通道为中介的易化扩散
C. 以载体为中介的易化扩散
D. 主动转运
E. 胞吐
The difference between regular mail and e-mail in terms of costs is______.
A. e-mail is many times more expensive
B. e-mail costs the receiver
C. e-mail costs nothing to send
D. e-mail saves the cost of paper
钠泵转运Na+、K+的机制是
A. 单纯扩散
B. 以通道为中介的易化扩散
C. 以载体为中介的易化扩散
D. 主动转运
E. 胞吐
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