A、<p><span lang="EN-US" style="font-size: 10.5pt; font-family: 宋体;">k=K<sub>a</sub></span><span style="font-size: 10.5pt; font-family: 宋体;">，且<span lang="EN-US">t</span>足够大</span></p>
B、<p><span lang="EN-US" style="font-size: 10.5pt; font-family: 宋体;">k>K<sub>a</sub></span><span style="font-size: 10.5pt; font-family: 宋体;">，且<span lang="EN-US">t</span>足够大</span></p>
C、<p><span lang="EN-US" style="font-size: 10.5pt; font-family: 宋体;">k<K<sub>a</sub></span><span style="font-size: 10.5pt; font-family: 宋体;">，且<span lang="EN-US">t</span>足够大</span></p>
D、<p><span lang="EN-US" style="font-size: 10.5pt; font-family: 宋体;">k>K<sub>a</sub></span><span style="font-size: 10.5pt; font-family: 宋体;">，且<span lang="EN-US">t</span>足够小</span></p>
E、<p><span lang="EN-US" style="font-size: 10.5pt; font-family: 宋体;">k<K<sub>a</sub></span><span style="font-size: 10.5pt; font-family: 宋体;">，且<span lang="EN-US">t</span>足够小</span></p>