单选题
He has established himself to be a competent manager by his successfully handling several difficult tasks.
【正确答案】
C
【答案解析】借助搭配结构(……经珲)和句子中出现的词语(successfully handling“成功地处理”)判断答案应该就是C(胜任的)。definite adj“明确的，一定的”：effective adj“有效的，被实施的，给人深刻印象的”：deficient adj“缺乏的，不足的，不完善的”；qualified adj“有资格的”。