It's a constant struggle to try to keep them up to par.要让他们达标，需要不断努力。All the doors have been bricked up to deter vandals.所有的门都用砖堵了起来，防止破坏分子闯入。Across the river the railway track ran up to the pithead.铁轨跨过这条河直达矿井口。...

多达，直到，在于…，能胜任...

up to的音标：up to的英式发音音标为：[ʌp tu:]up to的美式发音音标为：[ʌp tu]...