Wemust______thattheexperimentiscontrolledasrigidlyaspossible.
A、assure
B、secure
C、ensure
D、issue
Thefarmerhadtowearheavybootsinthewinterbecausethefieldsweretoowetand________.
A、earthy
B、solid
C、dusty
D、muddy
Itisusefultoscience_______theearthasanobjectinspace.
A、toconsider
B、whichconsiders
C、considers
D、theconsiderationof
Heaskedmewhethermybrother________(fly)toBeijing.
Ipreferthisdiagram________thatone.
A、than
B、morethan
C、ratherthan
D、to