The pronoun "who" should be replaced with "whom" in the following sentences:
- Who do you think should be the next president of the science club?
- The water from the faucet has turned brown, but I'm not sure who to call about it.
Correctly revised, they would read as:
- Whom do you think should be the next president of the science club?
- The water from the faucet has turned brown, but I'm not sure whom to call about it.
The other sentences correctly use "who."