单项选择题
A．it may be out of human control B．it has brought about few benefits so far C．people still know little about it D．people are afraid of such technology
A．attacking the diseased cells with healthy ones B．controlling the growth of the cells C．detecting disordered genes in the cancer cells D．activating cancer cells by switching them on
A．unable to give birth to a child B．with physical and emotional problems C．short of time and money D．separated from each other for long