【单选题】下列哪项不能作为诊断二尖瓣关闭不全的依据
B.
心电图检查QRS波群低电压,Ⅰ、Ⅱ导联T波平坦或倒置
C.
X线检查左心房显著扩大,主动脉弓缩小,食管被扩大的左心房推向右后方
D.
超声心动图检查左心室前后径增大,左心房显著增大
E.
心尖区听诊闻及粗糙吹风样收缩期杂音,并向腋部传导
【单选题】女性,23岁,既往无心脏病史,流产后一周,出现急性细菌性心内膜炎,伴二尖瓣关闭不全的症状及体征,血培养有粪链球菌生长,最适宜的治疗为
D.
静点氨苄青霉素,每天12g,庆大霉素3mg/(kg•d),持续4周
E.
静点万古霉素,每天1g,持续4周,链霉素每天1g,用2周
【单选题】What is the purpose of a network mask?()
A.
It is used in conjunction with the wildcard mask to determine the number of hosts on a network
B.
It is used to define which parts of the IP address are allocated to host addresses and network prefixes
C.
It is used to hide subnets from external networks by masking the subnets with NAT
D.
It is used to differentiate a network as a classful network or a classless network
【单选题】What is the purpose of a network mask?()
A.
It is used to identify the maximum hop count of a subnetwork
B.
It is used to identify an IP address as either private or public
C.
It is used to identify the network to which an IP address belongs
D.
It is used to identify the total number of bits present in an IP address
【单选题】In a type of computer network, what does MAN stands for?
C.
Metropolitan area network
【单选题】What is the goal of QoS in a network? ()
A.
prevent packets from being dropped
B.
increase available bandwidth
C.
reduce hardware errors
D.
provide predictable network service
E.
eliminate propagation delay
F.
eliminate jitter and packet loss