Are there cases of tense confusion in Mandarin?
Yes! In colloquial mandarin, tenses are often used improperly. For example, "我睡了啊" literally means "I've fallen asleep", but since it's impossible for a person to speak while asleep, this sentence actually means "I'm going to bed".
Which type of base should you use to achieve kinetic enolates from ketones?
Bulky bases such as LDA.
When evaluating the volume of a portion of a solid sphere, which type of coordinate system should you use?
You can use either spherical or cylindrical coordinates, or even the Cartesian coordinates, depending on the shape of the portion you are evaluating. But in general, the easiest way to evaluate a dome-shaped volume is by using spherical coordinates.