A piece of news on BBC website has a title like this:<h1>"US to boost Africa pirate forces"</h1>I could not understand why they use a "to infinite" (<span style="color:#0000bf;">to boost</span>) after a Subject (<span style="color:#0000bf;">US</span>) in this case.<br/>Many thanks for any help !!!<br/><br/><del>Ngoc Thao</del>