При каких значениях a прямые y=2x+4 и y=10x+a пересекаются на оси абсцисс?

Вставить в предложения слова вместо пропусков: which, who, that, when, where, whose.

1.Now it is a general term for systems or technologies ...... are used in sending and receiving messages over a distance electronically.

2.There was a time ....... cave drawings were painted on the walls of caves and canyons to tell the story of people's culture.

3.So are fires ....... usually meant "danger" or "victory".

4.Ancient Egypt was the first country ...... birds - domesticated pigeons were used for sending messages.

5. 1843 was the year in ...... Samuel Morse proposed a way to give every letter and number a special code.

6. It was Morses's symbol code ...... we can still find used today.

7. It was Bell ..... managed to register it first.

8. Alexander Popov from Russia ...... invention of the radio came before Marconi's, did not patent it.

9. In1983, the military project Arpanet became available to universities and research centres, ...... finally gave birth to the Internet.

Сколько воды надо прибавить к 200 мл 68%-ного раствора азотной кислоты (плотностью 1,4 г/мл), чтобы получить 10%-ный раствор азотной кислоты?

какая связь образуется между литием и серой?