Письменно переведите текст. pentode when in an operating tube the screen-grid voltage is high, secondary emission does not return to the plate and passes to the screen grid. this re¬sults in a counter flow of electrons. to eliminate this counter flow, a third grid was placed between the plate and the screen grid and connected to the cathode. this grid is called a suppressor grid. since the suppressor grid has a negative potential it returns the secondary emission back to the plate and thus eliminates it in the tube. the tube containing electrodes - the cathode, the plate, the control grid, the screen grid and the suppressor grid - is called a pentode. the cathode emits electrons, the plate collects them, the control grid controls the flow of electrons, the screen grid helps the plate to collect electrons and reduces the capacity between the control grid and the plate, the suppressor grid eliminates the secondary emission.

1. В том, что мы не ставим перед ним вс глагол don't/doesn't, а используем отрицательную форму глагола (с частицей not).

I am not a doctor [не I don't be a doctor/I don't am a doctor]

We are not doctors [не We don't be a doctor/We don't are a doctor]

He is not a doctor [не She doesn't be a doctor/She doesn't is a doctor]

2. Так же - мы не ставим вс глагол do/does на начало предложения, но ставим одну из форм глагола to be (в зависимости от лица).

Am I a doctor? [не Do I be a doctor?/Do I am a doctor?]

Are we doctors? [не Do we be doctors?/Do we are doctors?]

Is he a doctor? [не Does he be a doctor?/Does he is a doctor?]

3. always (всегда), often (часто), every day (каждый день), every year (каждый год), every week (каждую неделю), usually (обычно), sometimes (иногда), seldom (редко) (подробный список можно посмотреть в Интернете)

1. He always askes a lot of questions.

2. She often complains of pain in her eyes.

3. They sometimes go to a dentist.

4. His wife works as a doctor here.

5. We always discuss such problems.

6. They usually visit their friends at the weekend.

7. I usually examine patients in Room Five.

8. The students always do such exercises at home.

9. The first-year students often translate texts with a dictionary.

10. You often speak too much.

11. Ann likes reading books about animals.

12. Sam and Kate usually visit their parents in summer.

13. The teacher knows these students well.