Question

用“或”與“且”填空使命題為真.

(1)若x＞-1________x＜2,則-1＜x＜2;

(2)若△ABC是等腰三角形________是直角三角形,則△ABC是等腰直角三角形;

(3)若元素a∈(M)∩N,則aM____________a∈N;

(4)若x∈R⁺____________x∈R⁺,則x∈R.

Answer 1

(1)且  (2)且  (3)且  (4)或

解析:分別由“且”“或”的意義得到.