18.8. употребите правильную форму глагола в скобках. a visit to st. petersburg last weekend we (travel) to st. petersburg. we (get) on a fast train at 3 o’clock. on the train my friend and i (talk) a little, (read) some magazines and then (sleep) for about an hour. the train (stop) only twice. it (take) us five hours to get to the north capital. at about nine o’clock we (come) to our hotel. the next day we (go) on a bus excursion about the city. fortunately, the weather (be) fine. we (start) from the nevsky prospect and (drive) along it to the neva. our guide (know) a lot of interesting facts, stories and jokes which she (tell) us with great pleasure. the driver (stop) the bus from time to time, and we (go) out to admire the wonderful churches, palaces, museums and the famous bridges. we (learn) a lot of interesting things about the city and its people. the bus (bring) us back to the nevsky prospect at about four o’clock in the afternoon. it (be) time for dinner. we (be) hungry and thirsty. we (enter) one of the many cafes, (find) a table and (sit) down. we (choose) from the menu what we (want the dinner not (cost) us much. it was in fact twice as cheap as in moscow. there (be) a lot of people around us. they (talk), (laugh), (drink) coffee. they (speak) different languages: english, italian, german, finnish. after dinner we (do) some shopping. we (buy) a few souvenirs and (go) to the hotel. we (be) tired but very happy

Last weekend we TRAVELED (travel) to St. Petersburg. We (get) GOT on a fast
train at 3 o’clock. On the train my friend and I (talk)TALKED a little,
(read)READ some magazines and then SLEPT(sleep) for about an hour.
The train STOPPED(stop) only twice. It TOOK(take) us five hours to get to the
North capital. At about nine o’clock we CAME (come) to our hotel. The
next day we WENT(go) on a bus excursion about the city. Fortunately,
the weather WAS (be) fine. We STARTED(start) from the Nevsky Prospect and DROVE
(drive) along it to the Neva. Our guide KNEW (know) a lot of interesting
facts, stories and jokes which she TOLD (tell) us with great pleasure.
The driver STOPPED (stop) the bus from time to time, and we (go) WENT
out to admire the wonderful churches, palaces, museums and
the famous bridges. We LEARNT (learn) a lot of interesting things about
the city and its people. The bus BROUGHT (bring) us back to the Nevsky
Prospect at about four o’clock in the afternoon. It (be) WAD time for
dinner. We (be) WERE hungry and thirsty. We (enter) ENTERED one of the many
cafes, (find) FOUND a table and SAT (sit) down. We CHOSE (choose) from the menu
what we WANTED (want). The dinner DID not COST (cost) us much. It was in fact
twice as cheap as in Moscow. There WERE (be) a lot of people around
us. They WERE TALKING (talk), LAUGHING (laugh), DRINKING (drink) coffee. They WERE SPEAKING (speak) different
languages: English, Italian, German, Finnish. After dinner we DID
(do) some shopping. We BOUGH(buy) a few souvenirs and WENT(go) to the
hotel. We WERE (be) tired but very happy

1. We need to decide how to celebrate your birthday,

2 You needn't to go to the shop. I have bought everything we need.

3. Pupils must wear uniforms at school. It's a rule!

4. They don't have to cook dinner. Mother has done it.

5. People mustn't cross the street when traffic lights are red!

6. You have to do morning exercises! It's very useful!

7. May I take your pen? I have lost my pen

8. My friend can't speak English, but he speaks French.

9. You shouldn't go out if you feel not very well.

10. I should to take my umbrella, it's raining

Объяснение:

the side surface of this pyramid consists of 6 isosceles triangles with a base 16 and a side 17.

Find the area of one triangle.

S = 1/2bh, where b is the base and h is the height.

The height is found by the Pythagorean theorem.

The height is equal to the square root of the difference between the squares of the side of the triangle and the half of the base. Half of the base 16 / 2 = 8

17*17 - 8*8 = 225. The square root of 225 is 15. The height of the triangle is 15. Then the area of the triangle will be equal to S = 1/2*16*15 = 120 and the area of the side surface of this pyramid is equal to the area of one triangle multiplied by 6. S1 = 120 * 6 = 720