题目

 Though suffering a serious injury, Rafael Nadal refused to _______ the game and went on.   A. give out                B. give in                            C. give up                    D. give off 答案：C潜水艇是靠改变    来实现下潜和上浮的．一艘潜水艇从海面下30m深处下潜至海面下50m深处，它受到的浮力将    ．（填“变大”、“变小”或“不变”）