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Please see if you all think I am right.

Correct the use of colons. Write "correct" if no errors.

1. The program has one shortcoming: felxibility. Correct

2. Our meetings are scheduled for: Monday, Tuesday, and Friday. No Colon

Our meetings are scheduled for Monday, Tuesday, and Friday.

3. We liked this car because of: its price, durability, and appearance. No Colon

We liked this car because of its price, durability, and appearance.

4. We liked three features of Ms. Cole's resume: her experience, her education, and her attitude. Correct

5. We are enthusiastic about the plan because: (1) it is least expensive, (2) its legality is unquestioned, and (3) it can be implemented quickly. No Colon

We are enthusiastic about the plan because (1) it is least expensive, (2) its legality is unquestioned, and (3) it can be implemented quickly.
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You're right on all of these.
In 1 and 4, if you remove the part after the colon you still have a complete sentence. In 2, 3 and 5 the continuatiion of the sentence is necessary if it is to make sense, so it should not be separated from the first part by a colon.
Comments  
J Lewis,

I really appreciate your reply.

Thanks,

Delly