C is badly worded, though, because it seems to imply that there are two possibilities of essentially equal probability (either (1) little polar ice melts OR ELSE (2) the water levels blah blah blah). That leaves B, which correctly implies that the melting of the ice is hypothetical.
B were it to do so [hypothetical] if it were to do so
'they' is an ambiguous pronoun that potentially refers either to 'antioxidants'/'compounds' or to 'health benefits'. at worst it refers to 'health benefits', the subject of the preceding sentence, by default. either way, you've got problems.
you can't say "jump at QUANTITY". here, "to" is correct.
on the other hand, if the word "at" is part of some other construction, such as a time marker, then it could appear:
consumer spending always jumps at the end of the year, when the holiday season arrives.
here, "jump at" isn't really a construction; it's just "jump", followed by "at the end of the year".
read about (someone or something)
To glean information about someone or something by reading something.
I'm reading about Abraham Lincoln, at the moment.
I remember reading about a that in a magazine a few years ago.
read of (someone or something)
To have knowledge of be familiar with someone or something as a result of reading about them or it (in something).
I read of his research in a science magazine.
Most people have read of her at some point or another.
D选项：定语从句that are not foreseeable需改为 that cannot be foreseen。细分成分可知，本选项是主系表结构，即，
weather conditions are not foreseeable.
这句话讲的是：天气情况是不可以预测的。它并不代表这个天气状况没有被预测出来。例如：
(1) The book is not touchable.
(2) The book is not touched
句(1)讲的是“书是不可触摸的”，这是在描述书的一种特征，即，可能这些书是电子书，总之它们是不具备可触摸性的。句(2)讲的是“书没有被触摸过”。即，这些都是真的书，只不过没被触摸过。
同理，本题讲的是“没有被预见到的天气条件”，而不是“那些不具备可预见性的天气”（可能是一些神奇的气象条件，类似于刚才例子里的电子书），因此本选项是不正确的。
在CD之间选，实际上就是时态的区别
"learning how to synthesize the growth hormone, scientists had to remove it painstakingly" -- dont know if its wrong, but I would still prefer C.
because, of the word "had" which suggests two actions in the past..so ideally, it should be "learned".
choice b: two problems
- 'it' is troublesome, because it seems to refer back to the early hominids' manner of walking (something that clearly can't be seen in modern human beings)
- bad parallelism: the first part uses a possessive construction, not the preposition 'in', so the second must use a similar construction
choice d:
- bad idiom: you can't say 'regard X to be Y' (just memorize this)
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C is badly worded, though, because it seems to imply that there are two possibilities of essentially equal probability (either (1) little polar ice melts OR ELSE (2) the water levels blah blah blah). That leaves B, which correctly implies that the melting of the ice is hypothetical.B were it to do so [hypothetical] if it were to do so