76 Young people of different nationalities

77 Ten

78 10 weeks

79 Do environmental research

80 English

VI

1-d

2-e

3-a

4-b

5-c

76. Young people of different nationalities

77. There are ten expeditions every year.

78. ten weeks (trong câu:  Each expedition lasts for ten weeks and takes 150 volunteers. )

79. The volunteers do environmental research. (trong câu:  Others work in national parks or help scientists to do environmental research. - cuối đoạn 2)

80. English (trong câu: To become a volunteer, you have to be between
you have to speak some English and you also have to be enthusiastic, flexible and hard-working members of a team. - câu cuối cùng của đoạn.)