Put the verbs in brackets in the correct forms to complete the sentences.

1. When I (to come) home, mother already (to cook) dinner.
2. Jane always (to help) her mother about the house. Today she (to help) her mother since morning.
3. Listen! The bird (to sing) a beautiful song.
4. What Terry (to do) when you (to meet) him?
5. How long they (to know) each other?
6. Why she (to come) home so late tomorrow?

I would like to say a few words about mosquitoes. They are very nasty insects. They parasites on all living beings: people, animals. In Russia, mosquitoes are relatively harmless, although there is a huge number of them in Russia. But, in southern countries, in the tropics, mosquitoes are very dangerous. Their bite can kill a person. Theу are malarial mosquitoes...  The disease that they carry is called malaria. The mosquitoes breed on a warm time..
Mhe хотелось бы сказать несколько слов о комарах. Комары очень неприятные насекомые. Они паразитируют на всех живых существах: людях, животных. В России комары относительно безобидны, хотя их огромное количество в России. Но, в южных странах, в тропиках, комары очень опасны. Их укус может убить человека. Это малярийные комары.. болезни, которые они переносят называется малярией. Комары размножаются в теплое время...

We use these animals for different purposes. For example,  people often use dogs to looking for illegal substances (drugs). In ancient times, people used pigeons called   messenger-pigeon to exchange information. More often than not  we see dolphins water shows, this is really exciting!

People often used horses as means of transportation, and  , for example, the sheep give us   wool which we so need.

About the question "Could animals be used as secret agent?", I think it's impossible. Animals can't be used as  secret agent, because the exchange of information is impossible.