In one day, Sue can change the oil on 20 cars or change the tires on 20 cars. In one day, Fred can change the oil on 20 cars or change the tires on 10 cars. Sue and Fred can gain from trade if Sue changes the ( ) and Fred changes the ( ).
A: tires; oil
B: oil; oil
C: oil; tires
D: tires; tires
A: tires; oil
B: oil; oil
C: oil; tires
D: tires; tires
举一反三
- When the ships is going to enter into the harbor, ______. A: change from diesel oil to heavy fuel oil for mail engine B: pump out bilge water C: change sea chest from lower level one to high level one D: test emergency generator
- Which of the following conditions indicates the dilution of diesel engine lube oil by fuel oil?（） A: Water discharging from the water outlet of the lube oil purifier B: Fuel oil discharging from the water outlet of the lube oil purifier C: Lube oil discharging from the water outlet of the lube oil purifier D: A change in the lube oil viscosity
- When the ships is going to enter into the harbor, ____. A: change from heavy fuel oil to diesel oil for main engine B: pump out bilge water C: change sea chest form high level one to lower level one D: test emergency generator
- Oil can be conveyed by pipeline from an oil region to a refinery.
- One of the tires of the truck exploded because of (). (over, load)