Somemoleculesarelargeenough________(see)undertheelectronicmicroscope.
Hefellasleepimmediatelylastnight;hemust________(be)verytired.
He________methathedecidedtoleaveonMonday.
Howlong________they________(dig)theditch?
You________gonow.It’sgettinglate.
Heaskedmewhethermybrother________(fly)toBeijing.