He is difficult of approach.  他很难接近。
We have to find a correct approach to the subject.
我们必须得找到学这门学科的正确方法。
3. require
(v.) 要求；需要。
【拓展】require sth.；
require sth. of / from sb.;
require sb. to do sth.;
require + that 从句（从句中用虚拟语气should+动词原形, should 可省略）。如：
The suggestion requires careful thought.
Do you require anything of me?
They required him to keep it secret.
His health required that he should go to bed early.
另外，require doing= require to be done,表示“有……的需要”，need 和want也有此用法。如：The floor requires washing.= The floor requires to be washed.
4． comparison
(n.) 比较，对比；常与between 或with / to　连用。如：