Решение:
Вставляем подходящую форму глагола 'to be' (am, is, are) в зависимости от подлежащего.
- The weather is nice today. (The weather — ед.ч.)
- I am not rich. (I — первое лицо ед.ч.)
- This bag is heavy. (This bag — ед.ч.)
- These bags are heavy. (These bags — мн.ч.)
- Look! There is Helen. (Helen — ед.ч.)
- My brother and I are good tennis players. (My brother and I — мн.ч.)
- Emily is at home. Her children are at school. (Emily — ед.ч.; Her children — мн.ч.)
- I am a taxi driver. My sister is a nurse. (I — первое лицо ед.ч.; My sister — ед.ч.)