同一回采工作面不得使用¬下列哪种支柱？（） ["不同类型","不同性能","不同厂家"]
Examine the structure of the EMPLOYEES table: Column name Data type Remarks EMPLOYEE_ID NUMBER NOT NULL, Primary Key EMP_NAME VARCHAR2(30) JOB_ID VARCHAR2(20) NOT NULL SAL NUMBER MGR_ID NUMBER References EMPLOYEE_ID column DEPARTMENT_ID NUMBER Foreign key to DEPARTMENT_ID column of the DEPARTMENTS table You need to create a view called EMP_VU that allows the users to insert rows through the view. Which SQL statement, when used to create the EMP_VU view, allows the users to insert rows?（） ["CREATE VIEW emp_vu AS SELECT employee_id, emp_name, department_id FROM employees WHERE mgr_id IN (102, 120);","CREATE VIEW emp_vu AS SELECT employee_id, emp_name, job_id, department_id FROM employees WHERE mgr_id IN (102, 120);","CREATE VIEW emp_vu AS SELECT department_id, SUM(sal) TOTALSAL FROM employees WHERE mgr_id IN (102, 120) GROUP BY department_id;","CREATE VIEW emp_vu AS SELECT employee_id, emp_name, job_id, DISTINCT department_id FROM employee"]
李先生，腹部被车撞伤5h，腹痛明显，伴面色苍白，四肢厥冷，体检：血压75/55mmHg，脉率140/min，全腹轻度压痛、反跳痛、肌紧张，腹部透视无异常发现。腹腔穿刺抽出不凝血液。 该患者腹腔穿刺液中血液不凝固的原因是（） ["凝血因子消耗","出血量过大","凝血功能障碍","腹膜有脱纤维作用","误穿人血管"]
采煤工作面顶板管理，要严格执行公司顶板管理“24字方针”，工作面顶板管理要切实做到下列哪些？（） ["支撑有力","护顶严实","棚架稳定","严格管理"]
主要依靠人来完成服务过程的服务，如美容、教学等被称为（） ["高接触性服务","高技术性服务","连续性服务","间断性服务"]
在矩形断面水平渠道中设一平板闸门，如图所示，闸门与渠道同为宽度b=4m，闸孔出流量Q=12m3/s，闸下收缩断面水深hc=0.4m，产生水跃与下游水流衔接，下游水深ht=1.4m，求跃前水深并判别水跃发生的位置。
