Hi teachers,<br/><br/>Would you help me this sentence structure? I don't understand why "has" is used and not "is"?<br/><br/>Excerpt:<br/><br/>When Spain capped it last year, the world's second-biggest solar market callapsed - and so <b><u>has</u></b> the price of solar panels, down percent in 2009.<br/><br/>Thank you.<br/><br/>Regards,<br/><br/>Tinanam