Which of the following is the right order to send an e-mail?

① Click on "Send".       ② Click on "Write a letter".     ③ Click on "To".

④ Write your e-mail.    ⑤ Click on "Subject". [ ]

A. ①, ②, ③, ④, ⑤

B. ②, ③, ⑤, ④, ①

C. ②, ④, ③, ①, ⑤

D. ④, ③, ⑤, ②, ①,

以下哪一疾病不伴血清IgG低下

A．X-连锁无丙种球蛋白血症

B．腺苷脱氨酶缺乏

C．X-连锁严重型联合免疫缺陷病

D．白细胞黏附分子缺陷病

E．Jak-3缺陷