If it's illegal for someone under 21 to drink, it should beillegal for them to drink and drive. That's a no-brainer.
如果不满21岁喝酒是违法的，那他们酒后驾车也应是违法的。这太容易理解了。
《柯林斯英汉双解大词典》
2
Clearly, the sale of such stuff ought to beillegal.
显然，出售此类物品应该是违法的。
3
Because of America's gun culture, guns will never beillegal in the US. Many foreigners who have spent so much time in China are happy about the Chinese lifestyle.