139. About 500 _______technicians are on strike because more than 8,000 assembly-line workers were laid off. (A) maintenance (B) maintained (C) maintaining (D) sustaining.
About 500maintenance technicians are on strike because more than 8,000 assembly-line workers were laid off. (A) maintenance 在此是形容詞,形容“technicians”的工作性質 (B) maintained 動詞 (C) maintaining 動詞 (D) sustaining.動詞