Darkness _____, so we had to stop our journey and stayed on a farm for the night.

 A. happened             B. spread              C. broke           D. fell

The modern history of Italy dates from 1860, ______ the country became united.

A. when        B. if     C. since    D. until

— Do remember to take this medicine three times a day with warm boiled water.

  — _________.

  A. Heard it          B. Made it           C. Got it            D. Taken it

Have you ever thought, “I wish I could take a year off and just travel around the world”? Well, three lucky American teenagers were able to do just that. The teens—two males and one female--got an all-expenses paid, yearlong hike to five continents.

This trip didn’t include any five-star hotels or shopping funs. Eighteen-year-old Jamie Fiel from Keller, Texas, 17-year-old Arsen Ewing from Canyon, California, and 16-year-old Tyler Robinson from Lincoln, Massachusetts, didn’t expect fancy treatment. They signed up for the experience of a lifetime, which included hard work, often uncomfortable accommodations, and encounters with some of nature’s most dangerous animals and environments.

Jamie, Arsen, and Tyler were among hundreds of high school kids nominated by their science teachers to take this trip. Earthwatch Institute sponsored (赞助) this adventure. Each year, Earthwatch employs thousands of volunteers worldwide to help with scientific research projects.

The group went all around the world to get a close look at the most pressing environmental issues of our time. Their assignments were as varied as their locations, and included measuring and attending pink flamingos in Kenya’s Great Rift Valley, and tracking giant sea turtles in Costa Rica.

As they worked with the Earthwatch scientists, Jamie, Arsen, and Tyler began to understand that we are at a critical moment in the life of our planet. Time for change is running out. As the teens went from country to country and witnessed different environmental dangers and challenges, they understood that solutions to important environmental issues start with the power of one person's actions. They realized that each of them can make a difference.

These teenagers went on the journey around the world _____.

         A．to experience the most serous environmental problems on the earth

         B．to bring the kindness of America to the other parts of the world

         C．to go on sightseeing around the world

         D．to call on more teenagers to join Earthwatch Institute

What’s true about their journey?

         A．They had to pay for their journey on their own expense.

         B．They often had to move from one hotel to another.

         C．They had to take great pains to collect environmental information.

         D．They received a warm welcome every time they arrived at a new place.

It can be inferred that Earthwatch Institute could be _____.

         A．an international university that takes in students from all over the world

         B．a TV station that makes programmes on the beautiful scenery of the earth

         C．a travel agency that organizes adventure trips specially for school children

         D．an organization that brings science to life for people concerned about earth’s environment

Here is such a difficult text _____ none of us can understand. 

Here is such a difficult text _____ none of us can understand it. 

A. as    B. which    C. that    D. where

The boy you lent the pen to _____ it. 

A. break    B. breaking    C. broke    D. to break

—I've made up my mind to go abroad next year, darling, what about you？

   —Well,_____ you're going ,so will I. 

A. if   B. why   C. when   D. where

Could you give us the reason why you didn't do as _____ ？

A. were told    B. to be told     C. told to     D. told

With a lot of difficult problems ________, the newly-elected president is having a hard time.

A. settled   B. setting   C. to settle     D. being settled

“What do you think made Mary so upset?” “_______ her new bike.”

A. As she lost B. Lost     C. Losing D. Because of losing