物质的唯一特性是（    ）

阅读下文，回答相关问题。
                                                                                     《吕蒙传》节选
        吕蒙字子明，汝南富陂人也。少南渡，依姊夫邓当。当为孙策将，数讨山越。蒙年十五六窃随当击贼当顾见大惊呵叱不能禁止。归以告蒙母，母恚欲罚之，蒙曰：“不探虎穴，安得虎子？”母哀而舍之。
         鲁肃代周瑜，过蒙屯下。肃意尚轻蒙，或说肃曰：“吕将军功名日显，不可以故意待也，君宜顾之。”遂往诣蒙。酒酣，蒙问肃曰：“君受重任，与关羽为邻，将何计略，以备不虞^①？”肃造次^②应曰：“临时施宜。”蒙曰：“今东西虽为一家，而关羽实虎熊也，计安可不豫定？”因为肃画五策。肃于是越席就之，拊^③其背曰：“吕子明，吾不知卿才略所及乃至于此也。”（节选自《三国志·吴志·吕蒙传》，有改动）
       【注】①虞：意料，预料。  ②造次：鲁莽，轻率。  ③拊（fǔ）：抚摩。

他对我很好。他总是主动提出帮助我解决学习上的问题。

He is kind to me. He always ____ ____ ____ me with the problems in my study.

医生给严重腹泻的患者注射0.9%的氯化钠溶液（生理盐水），其主要目的是（    ）

阅读下面短文, 从短文后各题所给的四个选项(A、B、C、D)中, 选出可以填入空白处的最佳选项。
    In the 4th century, there was a man called Saint Nicholas in Myra. He was very rich and 1 to help others. He also cared for the 2 very much. He often 3 many kinds of gifts, money and other 4 things to the houses of the poor. He did this at night 5so that no one knew, because he wanted no 6 . He just wanted to help others. At that time, there were three poor 7 in his town. Both of their parents died. They could hardly 8 enough money to make a living. Nicholas felt sorry for them and 9 to do something to 10 them. On Christmas Eve, when everyone was11 , Nicholas walked through the streets to the house where the three sisters lived. Quietly, he 12 onto the roof and dropped three bags of 13 into the chimney. It so happened that the three sisters had 14 their stockings before they went to bed. The stockings had been 15 by the fire to dry. When Nicholas dropped the gold, each bag fell into a stocking. The three sisters were surprised and 16 to find the three bags of gold in their stockings the next morning. Now they didn't have to worry about their 17 as they could use the gold to get food. Soon, the story began to get around. Other 18 began to hang up stockings on Christmas Eve 19 finding bags of gold when they woke up the next morning.
    Over the years, Saint Nicholas became associated (有联系的)with Christmas. The 20 of hanging stockings up by the chimney on Christmas Eve is known all over the world. And Santa Claus, famous for the red cape (斗篷)and the white beard, became the most popular guest to children on Christmas.