s economic development has made ______ rapid progressin the past 10 years, and young people have made ______ great contribution tothis progress.

________do you usually do at weekends— I usually do homework and help my parents with the housework.

He used to be afraid of the dark so he used to go tosleep _______the light _______.

The new product is beyond all praise and has quickly taken over the market ___ its superior quality.

Mom was usually busy ______ my younger sister during the night and she ______ have less sleep.[ ]