B4

Some of the natural wonders are known for their beauty. The Meteor Crater is not one of them. It looks like a big hole in the desert. It was caused by a meteorite hitting the earth thousands of years ago.
(past simple passive, т.к. метеоритный удар по земле послужил причиной, а не большая дыра в земле послужила причиной )

CAUSE

B5

The crater is 4,145 feet across, and 570 feet deep. It is the largest impact crater in the entire world.
(степень сравнения)

 LARGE

B6

When Europeans discovered it in 1871, they thought it was the top of a volcano.
(past simple, т.к. говорится об определенном событии в прошлом)

THINK

B7

Since then, scientists have explored/have been exploring the crater for many years, but there are still many secrets and mysteries hiding inside it.
(present perfect, т.к. говорящий хочет акцентировать внимание на результате. Исследование началось с какого-то момента в прошлом и продолжается до сих пор.

present perfect continuous, т.к. говорящий хочет акцентировать внимание больше на процессе, который начался в прошлом и продолжается до сих пор. )

EXPLORE

B8

One day last summer my nine-year-old daughter went off to the camp. All her things were packed in a small bag.
(past simple passive, т.к. её вещи были упакованы, а не сами упаковали ч.л.)

PACK

B9

Two weeks later, Anna came back home and I unpacked her things. Everything was clean and well folded. “Camp sure has changed you. Your things look much better than usual.”
(степень сравнения)

 GOOD

B10

“It was simple, Mom,” she answered. “I didn’t unpack. Many children did the same.”
(child – ед.ч, children – мн.ч.)

 CHILD