A、<img src="https://img.ppkao.com/2015-10/sunsuqin/201510281730216011.jpg">必收敛
B、当时<img src="https://img.ppkao.com/2015-10/sunsuqin/2015102817304539684.jpg">,有<img src="https://img.ppkao.com/2015-10/sunsuqin/2015102817310390466.jpg">收敛
C、当<img src="https://img.ppkao.com/2015-10/sunsuqin/2015102817312471494.jpg">存在时,有<img src="https://img.ppkao.com/2015-10/sunsuqin/2015102817314434109.jpg">收敛
D、当且仅当<img src="https://img.ppkao.com/2015-10/sunsuqin/2015102817320265605.jpg">均存在时,有<img src="https://img.ppkao.com/2015-10/sunsuqin/2015102817322045792.jpg">收敛
查看答案