What is the disadvantage for air transportation? （）

[单选题]（）is the disadvantage for air transportation?A . Quick but not safeB . Less frequencyC . It can’t lift heavy goodsD . the highest cost in all transport modes

[单选题]What is NOT a function of the air supply of a covered lifeboat?（）A . Provides air for engine combustionB . Pressurizes water spray systemC . Provides air for passenger respirationD . Prevents smoke and other noxious fumes from entering craft

[单选题]What is the effect of heated intake air on a diesel engine? （）A . Increases efficiencyB . Increases engine horsepowerC . Increases engine lifeD . Reduces engine horsepower

[单选题]What kind of products do the air carriers deliver? （）A . The high valueB . Low density or weightC . A and BD . To add cost

[单选题]what kind of products do the air carriers deliver? （）A . The high valueB . Low density or weightC . A and BD . Shortest time to transport

[单选题]What is one problem with traditional air-conditioning systems?A.The chemica

[单选题]What is the function of the chillers in a traditional air-conditioning syst

[单选题]What is the main rhetoric device used in \"The Pentagon was divided onthe a

[名词解释] 不利因子 disadvantage factor

[单选题]The disadvantage above mentioned can be overcome by （）A . combined transportB . More frequencyC . Fast trainD . More flexible