function ShowTab(i){
	switch(i){
		case 2:
			first_center2.className='first_center_bg';
			first_center3.className='first_center_bgright';
			first_center4.className='first_center_bgright';
			first_center_body2.className='first_center_body_show0'
			first_center_body3.className='first_center_body_show'
			first_center_body4.className='first_center_body_show'
			
		break;
		case 3:
			first_center2.className='first_center_bgleft';
			first_center3.className='first_center_bg';
			first_center4.className='first_center_bgright';
			first_center_body2.className='first_center_body_show'
			first_center_body3.className='first_center_body_show0'
			first_center_body4.className='first_center_body_show'
		break;
		case 4:
			first_center2.className='first_center_bgleft';
			first_center3.className='first_center_bgleft';
			first_center4.className='first_center_bg';
			first_center_body2.className='first_center_body_show'
			first_center_body3.className='first_center_body_show'
			first_center_body4.className='first_center_body_show0'
		break;
	}
}