There is a new problem involved in the popularity ofprivate cars_____road conditions need_______.A.that;to be improvedB.which;to be improvingC.where;improving D.when;improving請說明理由（充分）　　謝謝！！！

熱心網友

sth need to be done = sth need doing there be 后的定語從句引導詞用that

熱心網友

Aneed to be done 需要被做..