1. Though they may attain considerable accuracy in the perception of flat form.
    虽然他们可能获得相当准确的平面形态感觉,

2. Though they may attain considerable accuracy in the perception of flat form,
    虽然他们对平面形的感觉能达到相当准确的程度，

3. He had discovered a great law of human action without knowing it — namely, that in order to make a man or a boy desire a thing, it is only necessary to make the thing difficult to attain.
    他不知不觉发现了人类行为的一个伟大的定律——那就是，若要使人追求一物，只要让它难以到手就行了。

4. And we get paid for it and praised for it, which produces good feelings we may not necessarily be able to attain in other parts of our lives.
    而且我们还能因此得到报酬和表扬，这会给我们带来我们不一定能从生活的其他方面获得的良好感觉。