One may as well not know a thing at all as know it but imperfectly.
39. have only to do结构，此结构表示只须(消)就能的意思。
We have only to turn to that extraordinary discovery made by Edison to see the significance of it.
40. not (no) unless句型
No increase in output can be expected unless a new assembly line is installed.
41. betterthan句型
Better my life should be ended by their hate， than that hated life should be prolonged to live without your love.
42. as it were是一个非常常用的插入语，意思是好象，可以说等。
Apiece of iron near a magnet， though apparently separate from it ， feels， as it were， the threads of this attachment.
43. 复杂结构，在下面例句中，由于anyone的定语从句过长，把谓语must realize提到定语从句之前。
Though faith and confidence are surely more or lass foreign to my nature， I do not infrequently find myself looking to them to be able， diligent， candid， and even honest. Plainly enough， that is too large an order， as anyone must realize who reflects upon the manner in which they reach public office.
44. notany more than为：不能，正如不能.
One cannot learn to sketch and express himself graphically only by reading about it any more than one can learn to swim while standing by the pool.
45. By that as it may是Let it be that as it may的省略形式，是由be引起的另外一种假设结构，意思是虽然如此，尽管这样.
It is said that the nerve poison is the more primitive of the two， that the blood poison is， so to speak， a new product from an improved formula. Be that as it may， the nerve poison does its business with man far more quickly than the blood poison.
46. if at all是一个由if引起的主谓结构不完整的短句结为即将，即使等。
I can see only with great difficulty， if at all.
47. 由there引起的句型容易产生复杂的句子结构。
There have been opened up to the vast and excellent science， in which my work is the beginning， ways and means by which other minds more accurate than wine will explore its remote corners.
48. range from to结构。这是一个常见结构，译时很多情况下应变通处理，不能完全依靠辞典上的释义。
Computer applications range from an assembly line completely run by computers to a children toy responding to remote signals.
49. the way结构
I always thought she was a common-sense person who discussed things the way they ought to be discussed.
50. 复杂宾补结构
In recent years， the development of sensitive and accurate measuring equipment has made it possible to measure the acuity of hearing of any individual at different frequencies.
61. 英语的一个习惯用法是：当否定谓语think(believe)时，实际上是否定其后面的宾语从句。否定就落在宾语从句上。这样宾语从句就变成了双重否定，译时可以按双重否定译，也可按肯定来译。
It is a valuable work. I do not think anyone writes so well that he cannot learn much from it.
62. to have not(as) to see中的不定式也有否定意味。
He had not the good breeding to see that simplicity and naturalness are the truest marks of distinction.
63. It occurred to sb. that意为突然想到，It dawned on sb.that.突然想起等。 从句是想起的内容。
I remember once being on a bus and looking at a stranger. He suddenly looked back at me-i.e.our eyes met. My instinctive reaction was to avert my gaze. It occurred to me that if I had continued to maintain eye contact， I would have been rude and aggressive.