Similar words: challenge, challenged, scavenging, changing, engineering, engine, engineer, heat engine. Meaning: ['tʃælɪndʒɪŋ] 
adj. 1. requiring full use of your abilities or resources 2. stimulating interest or thought 3. disturbingly provocative.
adj. 1. requiring full use of your abilities or resources 2. stimulating interest or thought 3. disturbingly provocative. 
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271. Auto makers tentatively have agreed to drop litigation challenging the legality of state-level curbs on tailpipe greenhouse-gas emissions, people familiar with the matter said.
272. Everyone talks about Turn 8, which is a challenging corner, but there are plenty of other blind, fast and challenging corners.
273. Methods Mice were immunized with SIEA and SA respectively or together, killed on the 48th day after challenging infection with cercariae of S. japonicum to exam worm burden and egg burden.
274. 5Swiss ball sit-up This is more challenging than a normal sit-up because the instability of the ball forces the core muscles to work harder.
275. Unique design for the golfers fairway provides another highly entertaining and challenging for the ball field, golf enthusiasts to enjoy the fun shots.
276. The management of leukoma cornea combined with strabismus and the priority of penetrating keratoplasty or strabismus surgery are challenging.
277. Millions of young bloggers are challenging the conservative government of Iran, at great personal risk.
More similar words: challenge, challenged, scavenging, changing, engineering, engine, engineer, heat engine, mudslinging, upbringing, ringing, bring in, coming in, belonging, stinginess, discharging, length, chalk, lengthy, at length, lengthways, catch-all, arm's length, wavelength, hang in the balance, hallelujah, sullen, pollen, nonchalant, at arm's length.