Complete the sentences with the correct passive form of the verbs.
1. it's obvious that more research into the new medicine (ought to / to do) before it was made available.
2. the results of the experiment (must / to check) before they were shown.
3. not all health advice (may / to understand) in the past.
4. there's a possibility that we (might / to lie) to by the drinks industry about how much water we need.
1. It's obvious that more research into the new medicine ought to have been done before it was made available.
2. The results of the experiment should have been checked before they were shown.
3. Not all health advice may have been understood in the past.
4. There's a possibility that we might be lied to by the drinks industry about how much water we need.