Answer:
1. Isabels cheeks are rosy
2. My hair is long and blonde
3. His face is thin
4. Their skin is dark
5. Her dogs tail is short
6. My sisters legs are long
Is - two billion dollars is a unit, one unit so it is singular and you use the singular verb
think - scientists is a plural, therefore, you must use the plural verb form of think
Answer:
what story is this based on?
If you want to explain to a foreigner how to learn when to use these words, you can say that the go from more general to more specific (in: more general, at: more specific).
in: for objects inside other objects, or for location in a big context: year, country,
on: on top of other objects, or for location in middle-scale contexts: day, street
at: for location on a very small scale: moment (exact time), at specific address<span />
