DF4型内燃机车使用手动打风时必须先断开10K，再按2QA。
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密封圈的宽度不小于电缆外径的0.7倍，且不小于10mm，否则为失爆。
A. 正确
B. 错误
DF4型内燃机车在二级磁场削弱工况下，F电流大于3000A时，其不均匀度不应大于15%。
A. 正确
B. 错误
Examine the data in the EMPLOYEES and DEPARTMENTS tables. EMPLOYEES LAST_NAME DEPARTMENT_ID SALARY Getz 10 3000 Davis 20 1500 Bill 20 2200 Davis 30 5000 Kochhar 5000 DEPARTMENTS DEPARTMENT_ID DEPARTMENT_NAME 10 Sales 20 Marketing 30 Accounts 40 Administration You want to retrieve all employees, whether or not they have matching departments in the departments table. Which query would you use?（）
A. SELECT last_name, department_name FROM employees , departments(+);
B. SELECT last_name, department_name FROM employees JOIN departments(+);
C. SELECT last_name, department_name ON (e. department_ id = d. departments_id); FROM employees(+) e JOIN departments d
D. SELECT last_name, department_name FROM employees e RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id);
E. SELECT last_name, department_name FROM employees(+) , departments ON (e. department _ id = d. department _id);
F. SELECT last_name, department_name FROM employees e LEFT OUTER JOIN departments d ON (e. department _ id = d. department _id)
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