Turn the following sentences into the active voive

Ex1.Turn the following sentences into the active voive

1Last year a profit of two million pounds was made in the first six months, but this was cancelled by loss of seventeen million pounds which was made in the second six months.
2. The house where the dead man was found is being guarded by the police to prevent a from being entered and the evidence interfered with.
3. Your money could be put to good use instead of being left idle in the bank.
4. The owners went away last March and since then their houseboat has been used continuously by squatters.