a. present simple (hiện tại đơn)
- ...36% of the world’s population is still affected by poor hygiene.
b. present perfect (hiện tại hoàn thành)
- Infection and disease haven’t been eliminated entirely in our hospitals yet, but they have been significantly reduced.
c. past continuous (quá khứ tiếp diễn)
- ...up to half of Lister’s patients who had survived surgery were being killed by infections spread by germs.
d. will future (tương lai đơn)
- ...medical organisations will be challenged in the future by new infections and diseases...
e. present continuous (hiện tại tiếp diễn)
- Although hygiene in developing countries is being improved all the time,...
f. past simple (quá khứ đơn)
- Louis Pasteur and Joseph Lister’s revolutionary ideas about using sterile instruments in clean hospitals were adopted in the 19th century.
g. past perfect (quá khứ hoàn thành)
- ...they had been taught about the importance of cleanliness by their religious leaders.