You can improve your English ______ practicing more.
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.
In order to work better in the future, each of us must first of all know our ______ and weaknesses.
31. The engine of the bus was out of order and the bad weather ______ the worries of the passengers.
-- Why didn't Mike attend the evening party? -- He is a quiet boy; He loves reading at home ______ to parties.