Answer:
1. Scientists still haven't worked out what caused the death of the animals.
2. Two men held up a supermarket last night and stole $2000.
3. Always cut up the meat for the dog otherwise it will choke on it.
4. Once you have finished cleaning, you can go on with your job.
Step-by-step explanation:
Compound verbs are two or more verbs that make up a single verb, as in they are used as a single verb. There are different types of compound verbs, such as phrasal verbs (two verbs put side by side to form another verb but not joined together), those verbs with auxiliary verbs (helping verbs with the main verb), or those that make up a compound word ( two or more verbs joined to make a single-word verb).
The given compound verbs, though put together but not making a single verb entity, are known as phrasal verbs. The given sentences with their correct compound verbs are given as follows-
1. Scientists still haven't worked out what caused the death of the animals.
Here, the verb "work out" will be put in the past tense "worked up" because of the tense form used in "caused".
2. Two men held up a supermarket last night and stole $2000.
The tense form will be in the past tense as the event occurred "last night".
3. Always cut up the meat for the dog otherwise it will choke on it.
4. Once you have finished cleaning, you can go on with your job.