Question

ぽんぽん

関係詞の問題です。
上から2.3.1が答えなのですが、これらはなぜ前置詞をつけなくてはいけないとわかるのですか？
（3）など、後ろが完全文だから1。などではだめなのでしょうか。

(2) The science of medicine, ( ) progress has been
very rapid lately, is perhaps the most important of
all sciences.
さささ4
0 for as
② in which
③ since
33
SO
(関西学院大)
) he built his own house.
(3) These are the tools (
0 that
③ with which
2 with that
④ which
isin (青山学院大)
(4) Japan has one of the best education systems
66d al
in the world, a system/which is supported by a
society/(
valued highly.
① in which
③ when
) learning has traditionally been
② that is
ew ort おl
④ which
(東京薬科大)