A(n) ________ is a very small piece of matter with a negative electrical charge, found in all atoms.
举一反三
- A/An ______charge or current has the same electrical charge as an electron. A: passive B: active C: negative D: affirmative
- _______ the beginning of the 19th century did scientists know that all matter is made up of atoms.
- All matter is ________ of atoms. A: made up B: made C: made from D: made into
- They found it was very difficult to ____all these problems.(cope with)
- They found it was very difficult to ()all these problems. A: add to B: cope with