单项选择题
A.有利于抵消设备附属件安装后重量的影响
B.有利于现场施工作业的影响
C.有利于抵消设备运转时产生的作用力的影响
D.有利于抵消摩擦面间油膜的影响
单项选择题 Which of following best describes the main idea of the passage?（）.
单项选择题 A．30～40minB．24～48 hC．5～7天D．11～12天E．14天左右临床用下列失活剂封药所需时间儿童患牙用金属砷
单项选择题 第一节听下面5段对话。每段对话后有一道小题，从题中所给的A、B、C三个选项中选出最佳选项，并标在试卷的相应位置。听完每段对话后，你都有10秒钟的时间来回答有关小题和阅读下一小题。每段对话仅读一遍。听力原文：M: Mary, you have told me something about your parents. Are there any other people in your family?W: Yes. There arc still my grandparents and my brother,M: Oh. You are lucky to live in a large family.What are the two speakers talking about?A．The woman's grandparents.B．The woman's parents.C．The woman's family.