81. It ___________ (snow) hard now. We'd better ___________ (not go) home right now.

80. Tennis ___________ (invent) a hundred years ago.

79. English ___________ (speak) in Canada.

78. So far, many man-made satellites have ___________ (send) up into space.

77. The young trees must ___________ (tie) to the stick to keep it straight.

76. The mountain will ___________ (cover) with the trees in a few years.

75. Can the report ___________ (write)in English?

74. The Great Green Wall must ___________ (build) in the world.

73. English ___________ (speak) all over the world.

72. The English song ___________ (teach) now over the radio.