<p>1) Finds the error part:
Scientists have discovered that walnut trees (respond to) environmental stresses (such as) drought (by producing) significant (amounts of) a substance similar to aspirin. (No Error)</p>
<p>There is no error in the sentence; yet I think (amounts of) is incorrect because of the problem of Noun/Preposition Agreement. If we use "amountS of", the noun should be "substances", right? Can we use "amounts of" and "A substance" at the same time?</p>
<p>2) The question is after a passage. It asks to combine 2 sentences in a proper way.
"That claim may sound incredible. It is based on extensive fossil evidence."
The best answer is:
"As incredible as that claim may sound, it is based on extensive fossil evidence."</p>
<p>I have doubts about the pattern "As incredible as". From school we are told that the sentence pattern "as + adjective + as" should be used only in the comparison structure, to describe something is the same as another thing. But this sentence is not going to compare the "claim" with anything else. I think to use "As incredible that claim may sound" can be enough. Why use "as incredible AS"?</p>
<p>3) Please help me explain a sentence; it is correct.
"Oscar differed from most other African American silent-film directors in that his films boldly tackled many controversial subjects of the day."</p>
<p>What is the verb of the sentence? Is the Pattern after "in that" a clause? (Please use simple sentences to say the same thing in order to make it easy to understand.)</p>
<p>Thanks a lot!</p>