Can not get last_value while doing the aggregation query along with first_value

The sqls are like following:

insert into root.sg1.d1(time, s1) values(1, 1);

insert into root.sg1.d1(time, s1) values(2, 2);

insert into root.sg1.d1(time, s1) values(3, 3);

select first_value(s1), last_value(s1) from root.sg1.d1 where time >1 and time < 3;

what we get is: