Are the following sentences punctuated correctly?

Well, I never saw him!

The patient has, in the past had a problem with alcohol.

As there is no contraindication, a biopsy was scheduled.

The first and third are correct.

Re-think the second. See #4 in the link I sent before.

The nursery rhyme begins this way: “Mary had a little lamb. . . . And everywhere that Mary went, the lamb was sure to go.”

Yes, the following sentences are punctuated correctly:

1. Well, I never saw him!
- In this sentence, the punctuation is correct. The exclamation mark is used to show strong emotion or surprise.

2. The patient has, in the past, had a problem with alcohol.
- The punctuation in this sentence is correct. Commas are used to set off the non-essential phrase "in the past" to provide additional information about the patient's past history.

3. As there is no contraindication, a biopsy was scheduled.
- The punctuation in this sentence is correct. There are no unnecessary commas, and the sentence is clear and well-structured.