1.The days＿＿he spent in Australia were very exciting.
问题描述：
1.The days＿＿he spent in Australia were very exciting.
A./ (正确)
B.when
C.in that
2.I still remember the day＿＿I joined the Young Pioneer.
A.on the that
B.when (正确)
C.which
答
前一句,定语从句,即the days在后面从句中充当成分,后面句子作为定语修饰the days,所以选a.也可以用that/which.
后一句,状语从句,表示时间,所以用when