какая масса серного ангидрида и какая масса 10% раствора потребуется для приготовления 20% раствора серной кислоты массой 200г

помогите плиз скоро контрольная работа решите плизз В треугольнике abc угол b равен 100 градусам найдите угол BCA

 PRESENT SIMPLE AND PRESENT CONTINUOUS Put the verbs in the brackets into the right forms of the Present Continuous or the Present Simple Tenses:
1) He ... (to work) in the centre of Chicago. He ... (to be) at the office now and ... (to do) his job.
2) They ... (to read) a lot of books. They ... (to like) it. So now they ... (to be) in the library and they ... (to read) a new interesting book.
3) His father... (not to watch) TV at the moment. He... (to sleep) because he ... (to be) tired.
4) I... (not to drink) coffee in the evening. I... (to drink) coffee in the morning.
5) The baby always ... (to sleep) after dinner.
6) When you usually ... (to come) home from school? -I... (to come) at three o'clock.
7) Eric ... (to talk) about his holiday plans but Kenny ... (not to listen) to him.
8) Henry usually ... (to wear) glasses and now he ... (to wear) sunglasses.
9) Where your cousin ... (to work)? - He ... (to work) at a hospital.
10) Look at the sky: the clouds ... (to move) slowly, the sun ... (to appear) from the clouds, it ... (to get) warmer.

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