Put the verbs in the correct form. 1. Elena is saying that she............ (to go) to the country every weekend. 2. She has just told us that they ......... (already, to build) the recycling plant. 3. I remember that you ......... (to promise) to send the invitations by 12 o'clock. 4. We thought they ......... (must) use new farming technologies. 5. Everyone knew that the conference............ (to start) next Monday. 6. They felt sure they ......... (can) suggest an excellent solution to this problem. 7. From the latest reports we have learned that around 40,000 African elephants ......... (to be) killed each year. 8. The manager didn't know that his boss ......... (to go) on business trip. 9. The seeds grew well because the farmers ......... (to dig) the soil well. 10. Experts said that the effect of global warming ......... (to increase) desert area and ......... (to raise) sea levels.

Here are the answers with explanations: 1. Elena is saying that she goes to the country every weekend. (Present Simple, так как речь идет о регулярном действии) 2. She has just told us that they have already built the recycling plant. (Present Perfect, так как действие завершилось к настоящему моменту) 3. I remember that you promised to send the invitations by 12 o'clock. (Past Simple, так как это воспоминание о прошлом) 4. We thought they had to use new farming technologies. (Past Simple, выражает необходимость в прошлом) 5. Everyone knew that the conference would start next Monday. (Future Simple in the Past, так как действие относится к будущему относительно момента в прошлом) 6. They felt sure they could suggest an excellent solution to this problem. (Past Simple, выражает уверенность в прошлом) 7. From the latest reports we have learned that around 40,000 African elephants are killed each year. (Present Simple Passive, так как речь идет о регулярном действии над объектом) 8. The manager didn't know that his boss was going on business trip. (Past Continuous, так как это действие происходило в определенный момент в прошлом) 9. The seeds grew well because the farmers dug the soil well. (Past Simple, так как это завершенное действие в прошлом) 10. Experts said that the effect of global warming is increasing desert area and raising sea levels. (Present Continuous, так как это процесс, происходящий в настоящий момент)