67.（ ）

(单选题)Make a mark _____ you don’t understand. (单选题)It is unknown to us ____ the air crash occurred in the mount (单选题)As to the development, our country is working hard for a____ (单选题)It was hard for me to learn English, for ___ of my parents c (单选题)Since the print book is as ____as thirty dollars, I suggest (单选题)The little girl kept her eyes ____on the dolls for quite som (单选题)______the singer, a crowd of fans entered the hall. (单选题)With the increasing number of private cars, road accidents c (单选题)I insisted that he ____ there with one of his classmates tom (单选题)If it _____, the sports meeting will be postponed.