So can the movements of aphids when, having depleted the young leaves on one food plant, their offspring then fly onward to a different host plant, with no one aphid ever returning to where it started.
这句话前面是根据上文省略了动词并且倒装了吗,后面when这里为什么有逗号隔开,when后面接哪里,这句话的各部分和正常语序应该是?
But daily vertical movements by zooplankton in the ocean — upward by night to seek food, downward by day to escape predators — can also be considered migration. So can the movement of aphids when, having depleted the young leaves on one food plant, their offspring then fly onward to a different host plant, with no one aphid ever returning to where it started.
第一句主要结构为:
daily vertical movements by zooplankton in the ocean can also be considered migration
第二句表示the movement of aphids也可以被视作migration,用了常见的so+助动词+主语的倒装结构。
第二句可以简化为:
So can the movement of aphids when their offspring then fly onward to a different host plant。
因为when状语从句中主语their offspring前插入了having depleted the young leaves on one food plant,所以两边加了逗号。
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