同时: all at once|all once|at all once|at once
举一反三
- The phrase "once in a blue moon" in last line refers to______. A: all at once B: once for a long time C: once in a while D: once and for all
- They all tried to talk _______, but I couldn’t hear anything they said. A: all the same B: once again C: for once D: all at once
- Riddle: What is it that occurs once in a second, once in a month, once in a century, yet not at all in a year or a week?
- All of the plants on farms have been developed from plants _______ wild. A: once they grew B: they grew once C: that once grew D: grew once
- In the Latin square design, all treatments occur once and only once on each row and column.