单选题
Medicine comes in many forms. In its liquid form,
medicine affects the body very quickly. But the effects of liquid medicine arch'
t usually long-lasting. This is why pills and capsules (胶囊) are also
used. The pills and capsules being sold today arch' t perfect,
either. Pills dissolve in the stomach. The medicine in the pills is released
when the pills dissolve. But often, the pills dissolve too quickly.
Scientists have been trying to develop a pill that can release medicine
slowly over a long period of time. They have applied their knowledge of
plants to produce the "osmotic (渗透的) pump pill". The cell walls
of plants are made of cellulose (纤维素). Cellulose is a very porous substance.
Their holes are big enough to allow water through the cell walls. As water
enters a cell, pressure builds up in the cell. The pressure pumps other
substances out of the cell. These substances leave the cell through the
cellulose wall. This slow, steady process is called osmosis.
The osmotic pump pill is coated with synthetic cellulose. Liquid medicine is
contained in the pill. The holes in the cellulose coating of the pill are big
enough to allow water in the pill. As water from the body enters the pill,
pressure builds up in the pill. The medicine is then slowly pumped out of the
pill.
单选题
The passage implies that the osmotic pump pill is better than other
pills and capsules because______.
A. it releases medicine slowly over a long period of time
B. it helps to build pressure in the body
C. the medicine in the pill can affect the body quickly