if是连词,要连接两个句子.if you can't make a telephone call,you can send a text message.或者you can make a telephone call,or send a text message.再问一题：If it will be rainy tomorrow,I will stay at home.哪里错了？主句用将来时，从句用一般现在时。If it is rainy tomorrow,I will stay at home.或者If itrains tomorrow,I will stay at home.