Sentence:  To reinforce , and <WSD>sometimes</WSD> to replace , the simulated typography , Braque and Picasso began to mix sand and other foreign substances with their paint ; the granular texture thus created likewise called attention to the reality of the surface and was effective over much larger areas . 
Meaning of the word marked with <WSD> tags:  on certain occasions or in certain cases but not always; at other times for six months"