1·In theory I'm on call day and night.
理论上，我不分昼夜随叫随到。
—— 《柯林斯英汉双解大词典》
2·In theory, interactive advertising can engage viewers in a way that 30-second spots do not.
理论上，交互式广告能够以一种30秒广告做不到的方式来吸引观众。
3·In theory, you need molten iron in the core to generate one, but Mercury is so small, its core should have long since solidified.
理论上，你需要核心里的熔化铁来产生它，但是水星很小，它的核心凝固还要很久。
4·In theory, a girl may veto the spouse her parents have chosen.
理论上，女孩可以不接受她父母已为自己选择的配偶。
5·We could do this in theory by studying an enormous impact crater, known as the South Pole-Aitken Basin.
理论上，我们可以通过研究一个名为南极-艾特肯盆地的巨大陨石坑来做到这一点。