下图是甲、乙两种固体物质的溶解度曲线。下列有关叙述正确的是（）

    A proverb says, “Time is money”. But in my opinion, time is even ____precious than money. Why? Because when money____(be) spent, we can earn ____back. However, when time____(go), it will never return.

    It is known to all that the time we can use is ____(limit). Therefore, we should make use____our time more ____(full) to study hard so as to serve our country in____future. But it is a pity that there are a lot of persons____do not realize the value of time. They spend their precious time smoking, drinking and playing.

    In a word, we should form a good habit of ____(save) time. Do not put off what can be done today till tomorrow.