Упростить выражение a)(5x+2)²-20, b)27x²-3(3x-1)²

Заполните пропуски соответствующей формой глагола to be, to have.

     1. Those doors … black. 2. … these their children? 3. There … a mistake in my test. 4. There … three pens, two pencils and a book on her desk. 5. I … free time today. Let’s go to the park. 6. They … a dictation yesterday.