There are several reasons ___1___ this viewpoint. For one thing, learning itself is an actually complicated and painful matter, and as a result, it is _____2_____ for us to commit much more time even our whole life to it. ____3____, it is exceedingly obvious that we are easy to forget what we learned, and accordingly, the significance of lifetime learning cannot be ignored. For example, ____4___ vocabulary is commonly the first step of preparing for an English test. However, it is pretty difficult for us to put a huge number of new words in our mind. ____5_____, we can divide these words into some groups and spend some hours each day on it in order to remember and understand these words.(用括号中所给的词和词组的适当形式填空,主要大小写和形式的变化) ( for another, account for, advise, therefore, memorize)