一边是日益稀少的森林资源被砍伐，一边是大量秸秆不得不被付之一炬造成空气污染。能否以秸秆代替森林制造板材？烟台万华集团给出了肯定的答案，该集团自主研发，利用农作物秸秆作原料，改性MDI作胶粘剂的板材硬度可与水泥相媲美，据此完成小题。

关于我国人口和民族的说法，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.