.大学英语(专升本)阶段性作业2单选题1. He studied hard in his youth,_ contributed to his great success in later life.(3分)(A)that(B)it(C)what(D)which参考答案：D2. For a successful business, friendly and _ staff are essential.(3分)(A)lovely(B)hard(C)efficient(D)respectable参考答案：C3. We should be able to do the job for you quickly, _ you give us all the necessary information.(3分)(A)as if(B)provided that(C)in case(D)so that参考答案：B4. It is becaus
