After supper she would sit down by the fire, sometimes _____ an hour, thinking of her young and happy days.
Not ______that is best for nature is good for people. A anything B nothing C something D everything
The bell __ the end of the period rang, __our heated discussion.
_______cloning human embryos is not legal in many countries, some scientists are already pushing ahead with research in order to produce a cloned human baby.
________ the programme, they have to stay there for another two weeks. A Not completing B Not completed C Not having completed D Having not completed
When the boss came in, these workers pretended to________ carefully.