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A. Their destination is freezing.
B. The holiday is too short.
C. The weather will be agreeable.
D. They will miss their home.
电子显微镜下见突触的结构分为______________、______________和______________。其中______________是冲动不由电传递的佐证。
有中枢兴奋作用的药物是
A. 去甲肾上腺素
B. 麻黄碱
C. 异丙肾上腺素
D. 肾上腺素
E. 皮质激素