1. It's raining now. Come and stand below my tunbrella. (x)
It's raining now. Come and stand under my umbrella. (√)
below sth 是指“在某物的下方”，位置并不确定，如:I could hear loud voices in the market below my window.(我可以听到窗户下的市场人声鼎沸。) under sth是“直接在某物之下 (受其保护)”之意。
2. Can you imagine it being 25 degrees under zero outside? (x)
Can you imagine it being 25 degrees below zero outside? (√)
below zero / freezing 意为“在零度/冰点以下”，是固定用法。
3. To use four-letter words would be below a gentleman.(x)
To use four-letter words would be beneath a gentleman. (√)
beneath sb=not worthy of sb，即“有失某人身份”。
4. Vitamins are beneficiary to our health, but we should use caution when taking them.(x)
Vitamins are beneficial to our health, but we should use caution when taking them.(√)
be beneficial to sb/sth是“对某人/物有益”的意思，为固定用法。beneficiary是“受益人”的意思，如:Nick is the sole beneficiary of his father's will.(尼可是他父亲立下的遗嘱里唯一的受益人。)
5. The new medicine will benefit from untold millions of patients. (x)
The new medicine will benefit untold millions of patients. (√)
Untold millions of patients will benefit from the new medicine. (√)
benefit sb 是指“某物使某人获益”，即“造福某人”之意。benefit from sth是“某人从某物中获益”。
6. Besides the young, handsome son, the woman seems like an old maid. (x)
Beside the young, handsome son, the woman seems like an old maid.(√)
Beside the young, handsome son, the woman has three beautiful daughters.(x)
Besides the young, handsome son, the woman has three beautiful daughters.(√)
Besides a good companion, the dog can carry out duties.(x)
Besides being a good companion, the dog can carry out duties.(√)
beside是介词，意为“在……之旁”或引申为“与……相比较”，即beside = compared with, besides是介词兼副词，意为“除……之外”，即besides = in addition (to)。
7. She has become the most known anchorwoman on TV.(x)
She has become the best known anchorwoman on TV. (√)
She has become the most famous anchorwoman on TV. (√)
the best known = the most famous,均表“最为有名的”，为固定用法。
8. She lmows better than trusting him with money matters. (x)
She knows better than to trust him with money matters. (√)
know better than + 动词不定式，意为“不至于笨到......之地步”，是常用句型。有时候也可用know better(省略than + 动词不定式) 来表达同样的情况，如:Everyone thinks it was a mere accident, but I know better.(每个人都认为这只是一起意外，不过我可不这么认为。)
9. It's not better than a robbery to demand such a high price. (x)
It's no better than a robbery to demand such a high price. (√)
be no better than = be as bad as, 意为“简直就是…… ”. 用于较负面的情况。
10. In my country, children between three to six go to kindergarten.(x)
In my country, children between three and six go to kindergarten. (√)
“(年龄)介于……和……之间”，正确的用法是(aged) between...and....。