But the mutable tubercle bacillus proved an elusive target, becoming resistant to each successive drug tried.

易变的结合杆菌是个难以攻克的目标，它对当时试用的每种药物都产生了耐药。

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Now Slim works on acquiring another elusive target: the love of his people.

FORBES: The World's Richest People

And terrorism is the most elusive target imaginable.

ECONOMIST: Lexington

Slim Jim's target consumer niche is the elusive 18- to 29-year-old guy.

WSJ: Krave, Perky Jerky and Others Remake Beef Jerky as a Healthy Protein Snack