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.