He often works by rule of thumb.他通常凭经验办事.As a rule of thumb, a cup of filter coffee contains about 80mg of caffeine.凭经验估计，一杯过滤咖啡约含80毫克咖啡因。A good rule of thumb is that a broker must generate sales of ten times his salary ...
I used to collect stamps.我曾经集过邮。And some like to collect stamps because they are beautiful or rare.还有些人是因为它们漂亮或稀有而喜欢收集邮票.Where did you learn to collect stamps?你在哪里学集邮的?...