Foreigners often make some strange mistakes in Chinese when they study the most difficult language— —Chinese. We try to analyze typical sentences to correct these errors.
Sāntiān nèi, nǐmen ké yǐ bù kéyǐ zào hǎo jiàn?
False: 三天内，你们可以不可以造好箭？
Sāntiān nèi, nǐmen nénɡ bu nénɡ zào hǎo jiàn?
True: 三天内，你们能不能造好箭？
“能”和“可以”混淆。“可以”只强调有能力，“能”既强调有能力，还要有条件。句中询问三天内是否造得好箭，要求不尽造箭的人有能力（技术），还应有某种条件（如原料、工具等）。此句应该用“能”。
Here, 能 is confused with 可以. 可以 merely stresses capability, but 能 emphasizes the objective conditions as well. In the present sentence, asking whether the arrows can be finished within 3 days, to achieve the goal depends not only on the capability （the skill） of the arrow maker, but also on such conditions as material and tools. Thus 能 is the proper word to be chosen.
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