Tosucceedinascientificresearchproject________.
A、oneneedstobepersistentMatteristhename________(give)toeverythingwhichhasweightandoccupiesspace.
Thefloordoesnotlooksobadwhen________(sweep)clean.
How long ________ they ________ (dig) the ditch?
Wewerebusy________(get)thingsreadyforthetrialproductionwhenhephonedus.
I shall never forget ________ (meet) the late Premier Zhou during his inspection of our factory.
