1、困难:difficulty;difficult;hard;trouble;bump;rub。
2、例句:I now know that its not always easy to see what should be done and even harder actually to do it.现在我知道,认识到什么是应该做的并不容易,而真正去做就更加困难了。
3、Some users may be unable to see, move a mouse, or may face any number of challenges when using a computer.在使用电脑时,有些用户也许无法看见或无法移动鼠标,或者会面临很多其他困难。