71. Many teenagers love to watch a conjurer _______ tricks.

70. It is ______ for anyone to laugh at those who are in trouble.

69. On account of his illness, he ___ never ________.

68. Which students ____ the teacher ______when she spoke of the most promising ones?

67. Teaching is an art ______ science.

66. In teaching a foreign language, it is important for teachers _____ new teaching methods ___ our teaching process.

65. At last, my little son _____ to put his whole heart into his studies at school so as to keep up with others.

64. The performances given by these young people succeeded in _______ a dull play ______.

63. Employees with skills ________ in joint-venture enterprises.