В данном задании нужно вставить правильную форму глагола "to be" в настоящем времени (Present Simple). Он изменяется в зависимости от подлежащего.
1. Mathematics is very difficult. (Mathematics is treated as a singular subject)
2. Our football team is winners. (Team is singular)
3. There are many birds in the tree. (There are + plural noun)
4. The dishes are on the table. (Dishes is plural)
5. My teeth are white. (Teeth is plural)
6. How many students are there in your group? (There are + plural noun)
7. Are my shirts washed yet? (Question form, shirts is plural)
8. Not many cities are as big as Moscow. (Cities is plural, and the subject is 'cities', not 'many cities' in this construction, making it plural)
Ответ: 1. is 2. is 3. are 4. are 5. are 6. are 7. Are 8. are