Ihavebeenstudyinghereforfouryears,bynextsummerI________.
A、shallgraduateSomemoleculesarelargeenough________(see)undertheelectronicmicroscope.
Hardlyhadhefinishedhisspeech________theaudiencestartedcheering.
Ihavebeenstudyinghereforfouryears,bynextsummerI________.
Herefusedtotelluswhetherhe________(undertake)thejob.
Heaskedmewhethermybrother________(fly)toBeijing.