Would you please check if I answered these correctly?

a. I just bought CDs by Regina Spektor, John Legend, and Prince.

b. I just bought: CDs by Regina Spektor, John Legend, and Prince.

I picked B because d suffices fine for this.

a. Students, who study hard, should do well on the test.

b. Students who study hard should do well on the test.

I picked B because it didn't need any correction

a. Alex realized the outfielder had dropped the ball.

b. After sliding into second base, Alex realized the outfielder had dropped the ball.

I picked B because the after makes a better sentence.

a. Bob enjoys playing football, and Jim enjoys playing hockey.

b. Bob enjoys playing football and Jim enjoys playing hockey.

I picked B because they are saying pretty much the same thing.

all is correct, except for the first. I would pick A instead of B. I just bought CDs by Regina Spektor, John Legend, and Prince.

<<a. I just bought CDs by Regina Spektor, John Legend, and Prince.

b. I just bought: CDs by Regina Spektor, John Legend, and Prince.

I picked B because d suffices fine for this.>>

I'm not sure what "d" says. "A" is the correct answer here. If the colon had appeared after the word "by," it would be appropriate.

<<a. Students, who study hard, should do well on the test.

b. Students who study hard should do well on the test.

I picked B because it didn't need any correction>>

Right. Letter "a" is wrong.

<<a. Alex realized the outfielder had dropped the ball.

b. After sliding into second base, Alex realized the outfielder had dropped the ball.

I picked B because the after makes a better sentence.>>

Both are fine from a grammar standpoint (unless I am missing something).

<<a. Bob enjoys playing football, and Jim enjoys playing hockey.

b. Bob enjoys playing football and Jim enjoys playing hockey.

I picked B because they are saying pretty much the same thing. >>

The comma is wrong in letter "a." It should not be there. Better "b" is the correct answer.

OOps, I think that was me typing fast. For the first one witht he CD's I thought that it was Ok to separate witht eh colns, but I went back to the wesite that was suggested and it helped me understand a little better. Thank you so much.

Let's go through each question and evaluate your answers:

a. I just bought CDs by Regina Spektor, John Legend, and Prince.
b. I just bought: CDs by Regina Spektor, John Legend, and Prince.

The correct answer is a. The reason is that when listing items, a colon is not necessary unless you are introducing a list. In this case, you are not introducing a list, but simply stating that you bought CDs by three different artists. Therefore, option a is the correct answer.

a. Students, who study hard, should do well on the test.
b. Students who study hard should do well on the test.

The correct answer is b. The reason is that the use of commas in option a suggests that only the students who study hard should do well on the test. However, the intended meaning is that all students who study hard should do well on the test. Therefore, option b is the correct answer.

a. Alex realized the outfielder had dropped the ball.
b. After sliding into second base, Alex realized the outfielder had dropped the ball.

The correct answer is a. Although option b adds additional information about Alex sliding into second base, it is not necessary for the main message of the sentence. The sentence in option a already clearly states that Alex realized the outfielder had dropped the ball. Therefore, option a is the correct answer.

a. Bob enjoys playing football, and Jim enjoys playing hockey.
b. Bob enjoys playing football and Jim enjoys playing hockey.

Both options are correct, and your answer b is correct. The use of a comma before the coordinating conjunction "and" is optional in this case. Both options convey the same meaning. Therefore, option b is the correct answer.

Great job on your answers!