第1个回答 2009-08-19
seldom ,sometimes, rarely, occasionally
第2个回答 2009-08-19
between times; every once in a while; now and then; once in a way
once in a while
第3个回答 2009-08-19
occasionally
第4个回答 2009-08-19
occasionally,once in a while,now and then,at times,at times