He finds it hard to keep _____ with the change of society if he stops learning.
I shall never forget those years _____ I lived on the farm with the farmers, ______ has a great effect on my life.
Will you _____ the clock? It’s slow.
The Expo site should be _______ from anywhere in the city of Shanghai within 90 minutes by bus, subways and special taxis.
The doctor said jokingly that his own infection of the virus _______ the discovery of a vaccine (疫苗)of the disease.
-- Jimmy had a lot of parties recently.-- Yes, that might ______ why he didn’t do well on the test.