C
這是一個(gè)縮寫句,完整的句子是：
This is a family which is not very big and which is one where everyone is friendly to others.
結(jié)構(gòu)分析：
（1）which is not very big and which is one where everyone is friendly to others是由and連接起來(lái)的兩個(gè)并列的定語(yǔ)從句,修飾family.兩個(gè)which在各自的定語(yǔ)從句中都作主語(yǔ),都可以換成that.但不能省略.排除D.
（2）后一個(gè)定語(yǔ)從句which is one where everyone is friendly to others又包含了一個(gè)定語(yǔ)從句where everyone is friendly to others,修飾one.這個(gè)定語(yǔ)從句是“主語(yǔ)+系動(dòng)詞+表語(yǔ)”的結(jié)構(gòu),主語(yǔ)是everyone,系動(dòng)詞是is,表語(yǔ)是friendly to others.可見關(guān)系詞既不是主語(yǔ),也不是賓語(yǔ),因此不能用that,排除A、B.