tpo11閱讀-Orientation and Navigation - 英檢

各位好:

關於這篇閱讀最後一題6選3的第二個選項我文法不是很懂,因此句義不太懂

所以不知道為什麼不選它,問題如下

In one set of experiments, Kramer placed the box containing food at the
same point of the compass each time he put food boxes in the birds'
environment.

(1)
這句的主詞是Kramer,動詞是placed,後面又有一句he put food boxes in the birds'
environment,這樣有兩個動詞,所以那麼連接詞在哪呢?還是說裡面有省略關代?
一眼看過去我無法分析此句子的句型,不知道哪裡腦殘了,請網友幫忙
(2)
那麼為什麼不能選這個答案呢?



原文文章如下:

Gustave Kramer conducted important research related to the ability of birds
to orient and navigate.
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Answer Choices
○ Because caged birds become disoriented when the sky is overcast, Kramer
hypothesized that birds orient themselves according to the Sun's position.
○ In one set of experiments, Kramer placed the box containing food at the
same point of the compass each time he put food boxes in the birds’
environment.
○ Kramer demonstrated that an internal biological clock allows starlings to
compensate for the Sun's movement.
○ After several studies, Kramer surmised that an internal biological clock
allows some species of birds to navigate at night.
○ The role of environmental cues in birds' navigation is clear, for on
overcast days, birds use objects besides the Sun to orient themselves.
○ Kramer showed that night-migrating birds use the sky to navigate by the
stars.

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