根据所加工的袋口结构，开袋机分为（）和（）两类。

白茶加工工艺为（）——干燥。

用于物流信息的采集、存取、传输、处理等的物流设备是【 】

A．运输机械设备

B．装卸搬运设备

C．配送机械设备

D．物流信息与电子设备

Americans have four primary avenues for making friends: at work, at school, through a hobby or a (1) such as volunteer work and discussion group, or through a family or (2) .
In American culture, a job is more than the work that one performs between the hours of 9 a.m. and (3) . Work becomes a major socializing influence. Many young mothers who (4) their jobs to care for small children remark on the loneliness of their new lifestyles because they have lost their forum for (5) .
A great number of American employers recognize business social (6) and use it to build a family atmosphere on the job so that employees will feel (7) in their work environment. Some employers arrange company get-togethers in their home or at a (8) . American companies have at least one (9) annually, usually at Christmas time. Many corporations have (10) where employees and administrators alike dress (11) to play games such as baseball and volleyball.
Top American administrators often hold social gatherings (12) . Depending upon the size of the employer’s home and the number of (13) . These social gatherings may be picnics, pool parties, or (14) . If the company is large, an employer may hold what Americans call (15) . For an open house, the employer will invite his employees to come to his home (16) between 1 p.m. on a certain day. Those invited usually stay for (17) , chatting with the other guests and their host. People come and go (18) during the designated hours, and the host keeps refreshments, usually (19) or hors d’oeuvres and beverages, available for all who come. For such social gatherings, it is considered (20) the invitation unless you have an excellent reason.

一般不入血的细菌是（）

A.志贺菌

B.伤寒沙门菌

C.鼠疫耶尔森菌

D.布鲁杆菌

E.单核李斯特菌

锅炉打焦工作时，应采取什么措施？