Choose A, B, C, or D that best completes each sentence. They don’t forget _______ a short vacation in Cuc Phuong National Park last year.

Choose A, B, C, or D that best completes each sentence. _______ the desalination plant, the company could offer an effective solution to the problem of water scarcity.

Choose A, B, C, or D that best completes each sentence. The public praised the local farmers for _______      millions of trees on the surrounding hills.

Choose A, B, C, or D that best completes each sentence. Certain _______  in the atmosphere, such as carbon dioxide, methane and nitrous oxide, block heat from escaping.

Choose A, B, C, or D that best completes each sentence. We admired the Japanese _______ the city of Fukushima after the disaster.

Choose A, B, C, or D that best completes each sentence. All of the disasters resulted from_______ will continue to have a devastating effect on socio-economic development.

Choose A, B, C, or D that best completes each sentence. Methane is a far more active _______ than carbon dioxide, but also one which is much less abundant in the atmosphere.