The task is very difficult. I wonder whether we will be able to finish it in the ________ of any other helpers.

A．appearance

B．escape

C．spare

D．absence

许多重要产品，由于使用了低合金结构钢，不仅大大地节约了钢材，减轻了重量，而且也大大提高了产品的质量和使用寿命。