单项选择题 Things are now definitely on track.（）

单项选择题 -What do you think of my suggestion？-（）.

单项选择题 He avoided（）over the unpaved（未铺砌的）way by（）the new highway.

单项选择题 Can you（）your sister in that crowd of people.

单项选择题 （）can never be guaranteed by material things，no matter how expensive they might be.